Bangle.js 2 stuck in boot loop

could there be some kind of contact inside the button which gives it pressed state constantly?

Maybe... do you see the '====' going across the screen when the button is not pressed? If not then it'd show the button is working.

Also, if you release the button when '====' is going across the screen, can you get the Bangle to stay showing a DFU screen? If so then that's great - new firmware can be uploaded so when we can work out what is causing this we can just do an update to fix it