Yes, I got some answers. In my case the problem was a broken rotary switch. These were the instructions EHX support gave to me:
“A: Check that R22 is making contact and is actually 22K. (In my case this was OK.)
B: Measure some voltages with your multimeter set to DC Voltage? The maximum voltage will be under 10V.

1. Measure the voltage on pin 1 of U2. You should measure either a voltage under 0.2V (low) or a voltage that is greater than 8V (high).
2. Measure the voltage on pin 2 of U2. You should measure the opposite voltage as compared to what you measured on pin 1. If pin 1 was low, pin 2 should be high and vice versa.
3. Now move the ENGAGE switch to its other position and repeat the voltage measurements. The voltages at both pins should flip when you change the ENGAGE switch setting.

– If the voltages at both pins do flip, then most likely the problem is a bad U3.
– If the voltage on U2 pin 1 flips but not the voltage on pin 2 then most likely it is a bad U2.
– If neither voltage flips then the problem is either R22 is not making proper contact on both sides of itself or the ENGAGE switch has a problem.”

In my case the voltages didn’t change, but “since U2 Pin 1 is at 9.15V, R22 is doing its job of pulling up the pin. So the problem is with the rotary switch, S2.”