If you were able to move the negative terminal and it was loose, that is the likely cause. It certainly sounds like it.
Was the terminal corroded or loose? As far as the revving engine, when there is a voltage issue, the sensors and modules can go haywire. I suspect that is what happened.
If the terminal is loose or corroded, try tightening and cleaning it to see if that takes care of the issue. Here is a link you may find helpful:
The link title doesn't mirror your issue, but the procedure is what I would like to try.
Let me know if that takes care of the issue. If, however, you see the cable is in poor condition, then replace the entire cable.
Monday, July 11th, 2022 AT 10:17 PM