Check drive motor brushes. Turn steer wheel 90° and see if one or the other motor operates. Check contactors over for all 3 sides of tip condition. Check shorts to frame. Nothing higher than 18 volts. Brake switch on hand brake leaking.

You say 50.2 volts that sounds like surface charge have you put meter into battery cables and checked under load ? Sometimes the battery will show a charge until you turn on key and try to use the lift and then you can see it drop drastically