Mtx 2300 amp repair
 

Hi. New to the forum. I have my cousins Mtx Thunder 2300 to try to fix. The negative post was loose. So opened it up and it fell straight out. Inserted it back and re soldered. Got the amp back together hooked it up nothing. Negative terminal came loose once again. So I started reading and read a found the mosfets (didn't know what they were) and noticed that the old heat sink compound should be replaced. So I replaced the compound and re soldered the terminal again making sure the solder was good. Still nothing. I wanna learn about this so any help is appreciated. Love trying to fix things so please give me some tips on what to check.