I wouldn't take the transmission out until you are sure you need to. You need to clear the codes and start over. Have everything hooked up and start it. Put it in forward and reverse and watch what code comes up and when. I don't understand how it can have no pressure to the reverse clutch and not make a code. That pressure switch senses that. If the solenoid is activated and the pressure switch doesn't sense pressure, a code will come up. And furthermore, the clutch piston would have to be broken if the solenoid is working ok and trying to pressurize the clutch pack but the pressure is zero. That seems unlikely. At any rate a code should appear.