Speaking from experience, its not that difficult to open elevator doors from the inside. Its the outside doors that are a pain, if you are on the outside of the elevator. Also, if it had power to it, the emergency phone should have been working, why didnt he just call for help? And if he didnt call for help, how the heck did they know there was someone stuck in it?
Unless he thought he'd have to pay the workers who came to get him out, then he'd probably stay in there forever.