92 525i Lost all electricity like the battery was dead/disconnected

[JesterMeister]

So I was driving the other day when partway through my drive everything electrical starting flickering for about 5 seconds, and then went back to normal with seemingly no electrical issues. After I parked and I went to lock my car the central locking wasn't working. At that point I thought maybe the fuse for the central locking blew because of all the flickering crap. I came to find out that when I try to start the car that there just wasn't any power at all, like the battery had died or disconnected. I left my key in the on position and went to ask one of my coworkers if they could help jumpstart my car thinking the battery had died. When I went back to my car the power was all there and was working and I was able to start the car no issues. Any Ideas what could have caused this, like a majorly bad ground? or maybe a bad relay? I checked my battery's voltage and it was at 12.5v. Today I was going to go check the relays in the dme box and I found it to be pretty hot and so was everything inside, I did drive the car about 20 minutes earlier but how hot is supposed to get inside of it?
Thanks for any help in advance.

[shogun]

The e-box has a blower fan and a temperature switch 44 CEL for it http://bmwfans.info/parts-catalog/E3...trol_unit_box/ more pics https://www.bimmerforums.com/forum/s...ine-bay-is-hot
also check the 2 fusible links which could have a haircrack and sometimes work, sometimes not https://twrite.org/shogunnew/data/electrical.html
https://www.bimmerforums.com/forum/s...=fusible+links
fusible links is always near the battery, so if the battery is in engine bay, look there http://www.bimmernut.com/forum/attac...1&d=1227448527
2nd under seat http://www.bimmernut.com/forum/attac...1&d=1227449422
check ground cable from engine to chassis