For some context, my 2000 Ap1 will not start, I hadn't driven it in about a month, and when I went to turn it on, the battery was obviously cooked for some reason. I am not sure if I or someone left the key in the ignition, a light on, etc... Nevertheless, the battery was outputting very low voltage. I jumped the car and let it run for a while, and with a multimeter I could see that the battery was not taking a charge, the alternator is outputting enough energy as well. After getting it to run from jumping it, I tried jumping it again and it would not start. So I bought a new battery. It still would not start even with the proper voltage from the battery and a little extra from a battery jumper pack. When the key was inserted and turned, my Haltech CAN gauge (Hooked up to a Platinum Pro Plugin) would turn on and give readouts. In the process of trying to figure out the issue, the can gauge suddenly stopped working and I can not see the indicator light(if there is one) lit up on the ecu. The Battery is still outputting the correct voltage, at this point I have no clue what the issue could be. Any suggestions would greatly help!
Specs :
-Haltech Platinum Pro Plugin with wideband
-ID1050 Injectors
-FX300 Clutch
-Ohlins DFV coilovers w Sake Bomb lower rear forks
-T1r 70mm Exhaust
-Koyo radiator
-Haltech Can Gauge
-Newish spark plugs

 

I’m grabbing at straws here but could the ignition switch itself maybe be the culprit?

 

One issue is the alternator rectifier has been fried from a jumpstart with a dead battery. In a car with the engine running, that will flicker your dash lights and some other things.
Not sure about the rest.