Have you tried just holding the button down? On previous bootloaders the Bangle would turn on as soon as there was power, but sometimes if the watch got very flat that could cause issues since there wasn't enough power in the battery to turn the display on right away.
So now the Bangle stays powered off when the battery charges up again, until you hold the power button for ~1-2 seconds.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Have you tried just holding the button down? On previous bootloaders the Bangle would turn on as soon as there was power, but sometimes if the watch got very flat that could cause issues since there wasn't enough power in the battery to turn the display on right away.
So now the Bangle stays powered off when the battery charges up again, until you hold the power button for ~1-2 seconds.