This sequence of events is long and not sure this step by step list will help explain but here it goes anyway. Numerous issues so not sure if they are causal or a result of some umbrella of system failure. No noticeable issues prior...
Objective: remove rear seats
Ignition off, in park, battery connected. Power seats have a safety latch behind the rear window so I had to stop the bracket from latching in upright position which triggered a warning light on seat switch. Removed one seat then closed rear door.
After dinner tried to open rear door but power door wouldn't activate. Lifted manually and then the power door motor started clicking repeatedly. Tried to stop motor by clicking remote, door button, and button in next to steering column. None of them stopped it so I closed the hatch manually and pressed "Start/stop button" to hopefully initiate something that would stop the rear door motor.
Engine wouldn't start but a rattling started under the hood. At this time I didn't notice a MIL. It was the canister marked nitrogen (break booster accumulator?) vibrating. I tried ignition again, failed, panicked and disconnected battery. Silly of me to think pumping break harder would start the engine but that's probably what triggered booster to start vibrating. I a read a post here about pumping break 20x and it flushed like its supposed to, no more rattling.
Upon connecting battery back up and trying to start then I noticed the MIL "Check 4 wheel AHC system". It was parked in Lo using Park Assist. Multiple times testing disconnecting battery to reset and removing AHC fuse but won't turn over. Battery is ok with power seats, lights, and rear power door all operating fully.
I tried a work around for starting in emergencies where you click Start/Stop Button to enter accessories mode, put in park, with parking brake, press break pedal, and hold Start/Stop button for 15 seconds. Sounds like starter clicking away but no ignition. The engine doesn't move and no sound so I guess spark and/or fuel aren't combining. Worried I'd burn out the starter. So that's where I'm at now, I appreciate anyone's 2 cents