88 rx7 na wont start; no click or crank
 

A couple of days ago my car wouldn't start after work, I assumed something must've drained my battery because that happened before so I had a coworker jump start me and it fired right up. About 10 min later driving the car completely turned off. No radio, dash lights, nothing. Pulled over and I couldn't get anything to work besides my hazards and popup lights. Gf came to jump start me but it wouldn't start from that. Got a multimeter to confirm that my battery is completely fine. Fast forward a couple days I've done some research and reached out to some groups and I checked my grounds as well as all the fuses. All my fuses are have continuity and the main fuse was replaced and works fine. I had replaced my ignition switch about 2 months ago as well with a new one from atkins. Just to be sure I reinstalled my old one and also tested one from a local friend out of his working FC. No change. I replaced the battery terminal connectors as well and I get 12v to the main fuse, but somewhere between my ignition switch and the rest of the car I'm not getting any power. Someone had mentioned the starter being a possible suspect but the car turned off mid driving. This all happened after I installed a wideband o2 sensor and gauge, I have the gauge wired to my radio circuit and the correct narrowband signal being sent to the ECU. Could something from a wideband o2 cause this issue? Thank you in advance for any advice you might have!

Check the FE-01 connector.

Is this the same as the X-01 connector I saw on another thread? This is the one that is directly near the positive battery terminal?

Nope. Same area though - near the underhood fuse box. Single fat(ter) black wire, black connector on both sides.

I found the connector and tried to squeeze it apart to disconnect it because its stuck together and the car turned on! Gonna clean it up and hopefully get the connection reliable but I cant thank you enough! :D