gas button broken, how do I open gas tank

I am assuming the gas door has an electric actuator? if so, and you think there is a bad fuse, replace it

if the fuse is not hte issue then your actuator is jammed You can simply use a hard peice of plastic to keep from damageing your paint and pop it open by pushing the part that holds it open back. Then lube lube lube the hel out of the actuator with wd40 or replace it.

Sometimes, there's a manual release lanyard in the trunk behind a trim panel.