Iphone 4 dead for a month and won't turn on

My iphone 4 was left in the car dead for over a month and now I can't get it to turn on. I charged yesterday, during the night, and this morning using different cables and different outlets. I currently have it plugged into my Mac and iTunes doesn't detect it. I read about taking the battery out and heating it up with a blow dryer but I can't seem to get the screws off because I don't have a small enough screwdriver or nails. I've already done the hard reset a million times so please don't suggest that. It's pretty old but it was working fine when I used it last over a month ago. Please help!