Before installing AsteroidOS to your watch, make sure you are aware of the capabilities and limitations of AsteroidOS on the Moto 360 2015. The following table should summarize the current support of this watch:
The Moto 360 2015 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 pads of the watch, this can be achieved by removing plastic outer ring. This is fairly straightforward as the ring can be easily lifted by putting a fingernail underneath the small lip.
Then you can either solder to the appropriate pads or 3D print a dock.
See https://forum.xda-developers.com/showpost.php?p=76733989 on which pad corresponds to which USB pin.
See https://www.thingiverse.com/thing:4366014 on a 3D prinable dock that can be used to interface with the watch (Also needs pogo pins).
You can report any hardware support issue here.
sudo apt install android-tools-adb android-tools-fastboot
adb reboot bootloader
fastboot oem unlock
Follow the instructions on your watch's screen. Please note it may void your warranty.
You can now decide if you want to replace Wear OS definitively or try AsteroidOS as a dual-boot. 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.
fastboot flash userdata ~/Downloads/asteroid-image-smelt.ext4
fastboot flash boot ~/Downloads/zImage-dtb-smelt.fastboot
fastboot continue
or using Windows:
fastboot flash userdata %systemdrive%%homepath%\Downloads\asteroid-image-smelt.ext4
fastboot flash boot %systemdrive%%homepath%\Downloads\zImage-dtb-smelt.fastboot
fastboot continue
adb push -p ~/Downloads/asteroid-image-smelt.ext4 /sdcard/asteroidos.ext4
or using Windows:
adb push -p %systemdrive%%homepath%\Downloads\asteroid-image-smelt.ext4 /sdcard/asteroidos.ext4
Everytime you want to reboot AsteroidOS from Wear OS, run:
adb reboot bootloader
Then, if you are using Linux:
fastboot boot ~/Downloads/zImage-dtb-smelt.fastboot
or on Windows:
fastboot boot %systemdrive%%homepath%\Downloads\zImage-dtb-smelt.fastboot