You can report any hardware support issue here. Use the label
ray/firefish for issues specific to your watch.
The following list shows the state of the features of the firefish version of this watch.
The following list shows the state of the features of the ray version of this watch.
|Model Number||Model Name||Codename|
|DW6A1||Armani Exchange Connected Drexler||firefish|
|DW6B1||Misfit Vapor 2 (46mm)||firefish|
|DW6F1||Fossil Q Explorist HR Gen4||firefish|
|DW6D1||Diesel On Full Guard 2.5||firefish|
|DW7B1||Misfit Vapor 2 (41mm)||ray|
|DW7E1||Emporio Armani Connected Matteo||ray|
|DW7E2||Emporio Armani Connected Alberto 2018||ray|
|DW7F1||Fossil Q Venture HR Gen4||ray|
|DW7F2||Fossil Q Sloan HR Gen 4||ray|
|DW7K1||Kate Spade Scallop Smartwatch 2||ray|
|DW7M1||Michael Kors Access Runway||ray|
|DW7M2||Michael Kors Access Sofie HR||ray|
|DW7S1||Skagen Falster 2||ray|
|DW7T1||Tory Burch ToryTrack Gigi||ray|
|DW7T2||Tory Burch ToryTrack Tory||ray|
Model number and variants
The Fossil Gen 4 is marketed as different versions from different manufacturers.
This means that there are two known versions that are compatible with a range of Fossil Gen 4 watches.
These two versions are referred to as
ray. One difference between the two is that
firefish has a larger display than
Generally, models that start with DW6 are compatible with
firefish. Models that start with DW7 are compatible with
The Fossil Gen 4 doesn't expose a USB connection. It is however possible to connect to the watch using an adapter cable.
You will need access to the USB pads on the watch, this can be achieved by removing the plastic back cover. Using heat and a prying tool, it is fairly straightforward to remove. Pay attention to the flex cable that connects to the back cover to the topside of the PCB. It is recommended to start prying on the side opposite of the buttons.
Then you can solder wires or use a custom dock to connect a USB cable to the watch. The image below indicates the function of each pad.
Be careful when soldering wires to the pads as the pads on the watch are very fragile.
A 3D printable dock that can be used to interface with the watch, but requires pogo pins, is available to download here: https://www.thingiverse.com/thing:5083434. This is only tested with the Skagen Falster 2, other variants have different dimensions and might be incompatible.
Choose your variant
Install ADB & Fastboot
On Linux systems
with apt package manager
On Windows systems
sudo apt install android-tools-adb android-tools-fastboot
install the Google USB driver
Get the Google USB Driver ZIP
Download this zip file containing ADB & Fastboot from Android SDK
Extract the content to a folder of your liking.
Navigate to that folder using the Windows commandline (cmd.exe).
1. Unlock your bootloader
Unlocking the bootloader may void your warranty.
The unlock process will trigger a factory reset of Wear OS. Backup any data you do not want to loose.
Installing AsteroidOS requires an unlocked bootloader.
Accessing the fastboot bootloader menu on your watch can be achieved using ADB in Wear OS, as described below in step 1.1.
If you are familiar with the manual method to access the bootloader menu, you can skip to step 1.3
. Those methods are explained on the useful commands page
1.1 Enable ADB on your watch
1. Open the settings app
2. Open the System page
3. Open the About page
4. Tap the Build number 7 times to reveal Developer options
5. Open the Settings app again
6. Open the Developer options page
7. Enable ADB debugging
1.2 Reboot to fastboot bootloader mode
Enter the following ADB command in a terminal with your watch connected to USB.
adb reboot bootloader
1.3 Use fastboot to unlock the bootloader
With your watch now in fastboot mode, enter this command in a terminal to start the unlock procedure.
fastboot oem unlock
1.4 Follow the instructions on your watch's screenPlease note again, this may void your warranty and will wipe your userdata.
2. Install and boot AsteroidOS
Choose your installation type
You can now decide if you want to replace Wear OS definitively by flashing the system and boot image. Or try AsteroidOS as a dual-boot by sideloading the AsteroidOS system image and boot it only temporarily. The "real installation" provides the best experience but it is advised to make a backup of your data first. The "temporary installation" is a good way to try AsteroidOS if you don't plan to use it daily and intend to keep your previous OS.
- Real installation
While your watch is in bootloader mode, flash the userdata and boot partitions using Linux:
or using Windows:
fastboot flash userdata ~/Downloads/asteroid-image-*.ext4
fastboot flash boot ~/Downloads/zImage-dtb-*.fastboot
fastboot flash userdata %systemdrive%%homepath%\Downloads\asteroid-image-*.ext4
fastboot flash boot %systemdrive%%homepath%\Downloads\zImage-dtb-*.fastboot
- Temporary installation
Reboot to Wear OS, re-enable developer mode and ADB debugging.
Push AsteroidOS to the internal sdcard using Linux:
or using Windows:
adb push -p ~/Downloads/asteroid-image-*.ext4 /sdcard/asteroidos.ext4
Everytime you want to reboot AsteroidOS from Wear OS, run:
adb push -p %systemdrive%%homepath%\Downloads\asteroid-image-*.ext4 /sdcard/asteroidos.ext4
Then, if you are using Linux:
adb reboot bootloader
or on Windows:
fastboot boot ~/Downloads/zImage-dtb-*.fastboot
fastboot boot %systemdrive%%homepath%\Downloads\zImage-dtb-*.fastboot
3. Enjoy your new OS!
Bootloop of any kind or stuck boot process
Don't panic. None of the commands we advised you to use can damage or brick your watch permanently.
You can always go back to the fastboot bootloader menu, by using the manual finger combos for your watch
Verify that you used the correct image filesSome devices like the Asus Zenwatch 2, the Fossil Gen4 models and the MTK6580 watches have more than one system image supplied, for different variants with slightly different hardware. Most watches have a graphical fastboot menu that shows the correct codename for the watch. Others need to be identified using the hardware differences noted above in the install section.
Clean your watch and charger contactsEven in case the fastboot flash process succeeds with no errors, it can still silently fail due to connection problems caused by dirty contacts. Clean the pins and pads with isopropyl alcohol. Ideally using that old toothbrush you keep around for electronics cleaning or a microfiber cloth. Carefully sanding the contacts (e.g. with a nailfile) can help in case of obvious corrosion.
Ensure a stable USB connectionPut the watch and your computer on the same flat surface. Try to not move the cable connecting your computer and the watch during the whole flashing process. In case of worn or corroded contacts and pogo-pins that lost their springiness, it might be useful to attach the watch to its cradle or charging cable using duct tape or rubber bands.
Repeat the flash processSome users have reported needing up to five flashing attempts for a successful result.
There is a small chance that the image files were corrupted during download. We do not currently provide checksums for the files. However, if you download the files again under a different filename and then compare them with
sha256sum filename, the checksums must match.
Boot gets stuck even after repeated reflash
Congratulations, you might have found a new issue for us to solve. While this should not happen with stable builds, the nightlies are advancing quickly, and are not tested on all watches. You are likely using a nightly build, as the installation pages currently link to it. You can try again and install a stable build when available
To help us solve the problem, you could try to collect logs. It is possible that the watch does not show a UI but is already accessible using
in the state the boot process stops. In case SSH connection works, try the following commands to write logs to local .txt files.
ssh firstname.lastname@example.org "journalctl" > journal-watch.txt
ssh email@example.com "/system/bin/logcat" > logcat-watch.txt
or, if your watch presents an ADB interface, use the following commands:
adb shell journalctl > journal-watch.txt
adb shell "/system/bin/logcat" > logcat-watch.txt
In case no connection is available, it is still interesting to see if the watch leaves any traces in your local dmesg. Try to spot USB related messages in
sudo dmesg -w
while the watch is connected and booting. Record the log using the
sudo dmesg > dmesg-local.txt
You can share those logs in a new Github issue
tagged with the watch codename. For support chat, you are invited to join our Matrix channel
Watch only boots when powered via USB, but shuts off when booted while worn
This is a clear sign of a worn battery that will soon fail. Maybe you should replace it.
The boot process of AsteroidOS uses all cores of a watch to ensure a fast startup. This leads to power spikes during the boot process, which can completely shut down watches with worn out batteries. It has been observed that WearOS can still boot on watches with worn out batteries, but AsteroidOS cannot, depending on the progress of battery wear. However, AsteroidOS can usually still provide a useful 10-20 hours of uptime when the watch is worn once booted while powered up.
Batteries are relatively easy to replace on watches with screwed down backs. Glued back plates usually require creative solutions involving hair driers.
Watch successfully boots into the AsteroidOS user interface, but immediately reboots
This is a known behavior when the battery charge is very low. The watch usually recovers from this condition by simply boot cycling for some time. All watches also charge in fastboot or recovery mode. Letting the watch dwell on the fastboot or recovery menu screen for some time should fix the problem even faster.
Watch is not detected and all fastboot commands fail
When using Linux, try prepending
sudo to the commands to execute them with root privileges. If that works, you are missing UDEV rules for Android devices that would allow your user to execute the commands. Many package managers provide the
android-udev-rules, which avoids the need to manually set up these UDEV rules. If the package is not available on your system, you can follow the instructions at the official android-udev-rules repository.
On Windows systems, this usually happens due to driver issues. If you have installed an Android USB driver other than the official Google USB driver that we link to in the installation fields above, please remove it. Then reinstall the Google USB driver or update it by installing a possibly newer version.
We find that the Linux fastboot drivers are more reliable. It is very easy to create a bootable live Linux USB stick, for example, following these instructions at askubuntu.com, and then follow the above Linux installation commands after booting the live Linux USB stick.
have caused all kinds of random and hard to track problems for many projects using ADB and fastboot. If your ADB and fastboot still can't connect after following the steps above, it might be worth switching to a USB 2.0 port. If your shiny new computer no longer has such a port, a cheap USB 2.0 HUB may help.
USB 3.0 ports
ADB connection works, but fastboot does not?
fastboot oem unlock
command not working even though the watch could be booted into fastboot mode using
adb reboot bootloader
is a known issue on windows systems. It is caused by using a watch manufacturer USB driver with missing fastboot support. Try removing that one and install the offical Google USB driver
we linked above in the install section.
Fastboot command stops with error during the ~5 minute flashing process
Smartwatches are prone to lose a proper connection to their cradle over time due to sweat corroding the watch pins.
Clean the pins and pads with isopropyl alcohol and repeat the flashing process.
Try to ensure a stable USB connection by putting the watch and your computer on the same flat surface. Try to not move the cable connecting your computer and the watch during the whole flashing process. In case of worn or corroded contacts and pogo-pins that lost their springiness, it might be useful to attach the watch to its cradle or charging cable using duct tape or rubber bands.
Fastboot command displays "invalid sparse file format at header magic" when starting to flash the device
This is not a fatal error and can safely be ignored. Fastboot expects images to be in sparse format. When a raw image is supplied like in case of most of the AsteroidOS watches, fastboot converts it to sparse and shows above message.
Fastboot command crashes or hangs at "invalid sparse file format at header magi" (explicitly missing the "c" in magic)
This error occurs when using deprecated fastboot and ADB versions on Windows systems. If you already had adb.exe and fastboot.exe installed and skipped downloading our supplied ZIP file
, please install and try those commands instead. Another reliable source for updated windows ADB and fastboot versions is the official Google platform tools ZIP file