On Crown electric lifts, you do not use the frame for the negative when troubleshooting as it will not work.
Always use a negative cable connection.
Grounds to the frame be it positive or negative are not desirable, even though it is common.
Batteries are commonly guilty of bleeding voltage to their case which transfers to the trucks.
That explains your vom readings in your reply on your TB11 inputs.
Use a proper negative, and try the TB11 inputs again.
You need to block up the drive wheels, verify the steer wheels are straight ( safety reasons) and have an operator ask it for fwd travel (creep speed)