GFI not working-blew 2 30 amp service fuses

I have a meter, but all I have tested with it is batteries :( I will google how to test breaker. I flipped all breakers back and forth, so I don't think they are issue as far as not being reset. Fuses aren't blowing anymore, just first time issue started. When I was trouble shooting last time, it was after 3 day trip and camper was in street with no AC in 110 degrees. I had to stop because I was about to pass out. I'm not certain if any AC is working at this point. If I remember correct, by the time the generator breaker started flipping after replacing GFI, NONE of the plugs, GFI or otherwise worked. Initially my other non-gfi outlets were working. I could have been a bit delusional at the end of this before I put it in storage :) I will test breakers as soon as I can get back to trailer. I recently replaced the 30amp breaker (it dry rotted apart) that the battery lines go through at front of trailer where battery connects. Any chance this could be part of issue. It was working, but maybe it blew?
Patty