i have an 89 toyota camry please help with info on getting door open it will not unlock at all

Greetings. I have an 1995 Jeep Grand Cherokee Orvis edition with full time 4 wheel drive. I have been having problems with my front differential ever since I've owned it. Last spring after a muddy offroad adventure, on my way home, the front dif started howling. Upon getting home and inspecting the dif, I noticed that the spider gears were chipped. So I brought it to a transmission specialist place because they are supposed to be good with drivetrains. He told me the whole dif had to be rebuilt. So I ordered new spider gears, ring and pinion, bearings and seals. They were put it. Then later that summer, I started having problem with the front tires locking up upon hard turns. Upon inspection, I noticed the CV joint boots ripped. So I got new boots, took the joints apart and repacked them with grease. Problem sort of went away. This past Christmas I purchased replacement axles with U-Joints instead of CV-Joints. I did this because I felt U-Joints were stronger. The tires started binding again upon hard turns, and the front dif is howling again. I don't want to spend another $1500 on fixing it. (the dif) This is my question, or series of questions: Any idea what could be causing these frequent failures? I want to fix it myself. How hard is it to rebuild a dif? I've done alot myself on the grand now. Could I get a third-member from a scrap yard and swap it? Would that be the easiest fix? Thanks for your input.