Originally Posted by ElectroBoy

Now that you’ve been spanked by Toyota back to the OEM baseline it will be a waiting game until, or if, it happens again. You’ve probably already tried to reenact the sequence of events that triggered the failure. Once you’re as confident as you can be that all is well you could try adding in one LED mod at a time and again trying to get it to fail.

I can’t imagine how any interior lighting LEDs would cause a problem, especially when there is no power applied to them. However it is conceivable that aftermarket headlight replacement LEDs, or high power brake or reverse LEDs, could be radiating or conducting EMI into the chassis ground and occasionally causing an ECU glitch. But only when they are powered on.

It may be worth an experiment at some point to reconnect your auxiliary reverse light and see if that was the culprit.