Yesterday, I started getting absurdly high readings on the second INA channel. It turned out that the onboard 0.1 Ohm shunt resistor was broken or disconnected. Fortunately, it is easy to use an external shunt instead. Cut the trace SJ4

and add a 0.1 Ohm resistor across the load and the supply pin.

The next board revision should have the shunts external.

Next, I had a short circuit with smoke coming off the board. Some traces burned off and lifted off the board.

I think what happened is that when I added the external shunt, I must have cut the wire with the grinder.

So the red cable that was connected to the battery got punctured and shorted with ground. Remedy: only run additional cables on top off the board. I also added a re-settable fuse to the power control board: