sounds like your motherboard is playing silly buggers.

My first action would be to reset the firmware back to factory settings - usually there is a reset option somewhere in the printer control panel.

Failing that, a new board sounds like a good idea.

It seems to have reversed movement, and lost thermal control.
The obvious candidate would be the board. It might have overheated on that long print.

But definitely a soft reset would be the first thing I'd try.

And good to see you around the forum again :-)