Hi, i have a 2001 nissan altima gxe. Recently I went out to start the car and wouldn't start. I took the battery out of my tractor to use it not realizing the negative and positive were reversed on it. So i put it in backwards! So I've checked all fuses and everything checks out. I got a new battery and alternator also. The car starts up fine but none of the electrical is working and not changing gears. Also at the 100A fusible link the previous owner has it bypassed and it's just two metal pieces pinched together, no fuse. So when put my multimeter ans touched the negative battery post and the place where 100A link goes everything will start back working? But when I cut the car off it stops working again! So im not sure if there could be a short or something! So if anyone has any information that could help would be greatly appreciated!!! Thanks so much!