IPad infotainment blackout followup. Former coder and tester here too.
System was working normally when the IPad (smaller IPad Pro) was plugged in, and continued to work normally. Car turned off, IPad left plugged in. Restart car, no infotainment. Tried to find a reboot shortcut, you know, holding down various keys together in sequence, couldn't find the secret handshake. Unplugged IPad, restarted car, oh oh, no infotainment. Went in for lunch, came back out and restarted, all OK again.
Reminds me of the good old days, when all else fails pull the plug, go for lunch, then try again. Amazing how many times that used to work.