1994 Toyota Celica No Power! 12.6V Gauges flipped over craz

Ok I have a 94 ST, just got a 60k 7A-FE (from a 95) put in, a couple weeks ago. Think the ECU might be gone? HELP
The other day I driving and my stereo stopped playing and felt like my car lost all power, then my stereo said "initial" which it has only said when I put a dead battery in. I thought not much of it but then the next day it did it again and then the interesting stuff started happening.
My car was driving fine, then started loosing power, and my Gauges went crazY! Ups and downs, stuff was beeping and I put the blinker on and it blinked as if one was out (FAST) and then my car shut off. Went to start it and got nothing. Thought it might be the stereo, maybe blew a fuse somewhere. Unhooked the battery, pulled out the stereo on the side of the road, taped all the powers off, checked all the fuses in the car (none blown). Hooked back up the battery, started up, but the gauges went crazy for a second and it idled higher than normal.
Got where I was going, seemed to be okay. That night was driving back home and it started again lost all power, then got it back (engine I dont think stopped) the car was jerking back and forth as I was hitting the gas, again gauges going crazy, very weird experience.
Got to my cousins house and the car was running turned it off and went inside for a second. Went back out, the dome light came on, closed the door, put the key in and the gauge "warnings" came on, as normal, turned and got nothing. Opened the door and the domes were out. Checked BOTH my batteries, 12.6V. Unhooked the back one completely, checked all the grounds (all 1/0 Gauge, BRAND NEW) All grounds are good, unhooked the battery, figuring it would reset the ECU? (Right?) So I got the dome lights again and the same thing happened. Absolutely no POWER ANY WHERE, no domes. NOTHING.
Batteries are perfect, no blown fuses anywhere, grounds all good.
How do I check the larger fuses? Is there a way to tell, or like a "main fuse"?
Thinking its the ECU? HELP, can someone tell me where its located, and if they think that the ECU is whats bad?
Thanks in advance people! Biggrin. Gif