If the fault causing your 20 volt midpoint is due to the input FET not conducting then both will be cold because no current can flow in either due to Q1 (the lower FET) being off.

If you add the resistor across the FET you turn Q1 fully on. That means little voltage is across it but it still sees the full output stage current of around 1.6 amps. Q1 runs cold. Q2 however sees around 22 volts across as well as the current. Q2 gets hot (power is volts multiplied by amps).

So the input FET not conducting and adding the resistor as a test give two different scenarios. Both will give 20 volts midpoint but one (non conducting FET) has no output stage current flowing and the other (adding the resistor) should see the full 1.6 A