I just had my 2011 traverse in the shop for a transmission rebuild. When I got it back home, it would not crank and the fuel gauge indicated empty. I searched the forum and found a thread which recommended the ECU ground on the harness, and I found it on a stud on the transmission, but loose and not bolted down. I bolted it up and everything seemed normal, then today it happened again. I jiggled the wires around the ECM and suddenly it was fine again. I believe it is a ground or an CAN bus issue, when it happens the rear hatch won't open and I'm sure there are other communication issues. Also the ECM feels loose in it's mounting. Before I take it back into the shop is there anything else I can check?