1.) Turn off the watch
2.) Hold down the button until you feel it pulse twice, then release. (I had to have mine on the charger to get it to start) It vibrated once, and then twice.
3.) Bootloader should show up, quick press to change the mode from Normal to recovery mode, then long press to start recovery.
4.) Android Robot should pop up. Press the button again.
5.) You should now be able to swipe to select wipe cache, pressing the button to select, then again to do the factory reset.
6.) Now select reboot.
I can't say whether this solves the issue or not, I'm still waiting on mine to finish charging enough to do the initial load. Fingers crossed!
*UPDATE* It didn't solve the issue. It at first appeared to as it ran smoother than usual and longer than usual, but still randomly shut off. :-(