Posted in the FB groups, adding here to to cover all resources

Issue:
-Installed used MSPNP1, using TS Lite for now.
-Installed ECU according to instructions and loaded no AFM basemap, laptop connected just fine.(I could hear the fuel pump priming too)
-Went to start to set base timing, had low battery voltage from the car sitting so it only cranked for .5 sec then the relay just clicked.
-Charged battery, turned key to ignition and I don’t hear fuel pump priming and laptop won’t connect to ECU anymore. Car just cranks and wideband reads 10.0

What I have checked and what's also installed:(If it matters)
-All fuses under hood and in kick panel are good.
-ST SIGN fuse removed
-TPS is still connected
-AFM removed and GM IAT installed right before the throttle body
-AEM UEGO 30-4110 installed and I have the white wire running from the gauge to the factory O2 wire under the hood.
-Car started with no issue the stock ECU, haven't plugged it back in to see if it will fire
-Using FTDI USB to serial adapter

Thoughts on what may have happened while cranking on low battery voltage or what I can test next? What gets me is everything seemed to be working just fine right before I tried to start the car on a low battery.

 

PNP1 suicided itself after it realized it was 2018

(sorry, no idea but sounds ecu is not even powering on... if all fuses are good I would try it back on the stock one, you don't need tps and st-sign but you need AFM in place)

 

Problem solved, turns out I needed to unplug the TPS. Still don't understand how/why that would keep my laptop from connecting to the ECU in the first place but that's for another day, on to the next issue lol.