At this point, the only thing that makes any sense to me is to have the EQ heads repaired, put them back on...... put the motor back in.

Should be able to read what’s going on with the sensors, etc, in real time with a scan tool..... right?

If things look amiss, try the other computer.

I really don’t ever work on computerized engines at all, but I seem to remember having a conversation with someone once about breaking in a new motor in a car with cats, and they were saying how running at a high idle without the car moving and having air running around the cat that they can overheat and fail.
I don’t know if this is true or not....... but perhaps there’s some truth in it, and your two night garage run in sessions compromised the cat from the start.