Re: iphone power button is stuck and it wont turn on
Best bet is to take it to the apple store and let them handle it, could be a simple repair for them.
Anything that you try on your own risks further damage and with a non removable damage I can not in good conscience suggest anything else to you! And even with a removable battery the steps I would suggest STILL run risks.
Ok a couple quick things you can try, lightly VERY lightly spray compressed air around the button, do NOT use a full spray. Also try lightly tapping the button and see if you can get it to spring up again here lightness is key you don't want to damage it further, you just want to get it to bounce out IF it's only stuck down. In all likelihood the button is broken and needs to be repaired and the apple store is your best option.