Thank you for making that check. You may very well be right about the pot…But i do think you need to take the microcontroller out and test it again without it in the circuit. What if the microcontroller has an internal short or partial short to ground?…you could get the same test result. Testing components in a circuit can be kind of tricky because you have to consider everything else that is attached to that circuit node. The microcontroller pins are supposed to be high impedance (over 1M) but it is possible for each pin’s internal resistor to become damaged. I’m sorry I mislead you in my previous directions, I forgot about this contingency. And sorry to have you keep working on this, but it’s important to get an accurate diagnosis.
Let me know what you find.
-Brach