Sorry for the lapse in response - we resolved the issue a few days ago. After testing multiple systems we found the oldest problem in diagnostic history - taking the customer's description of how / when the problem presented at face value. The customer told us that the unit failed to operate in the bay where is was charged and had not been moved. Not the case. They had pushed the unit into it's resting place and in turn caused the steering wheels to extend beyond their allowable angle. We manually repositioned the wheels and BINGO. Of course the over steering caused damage to the steer encoder as well as the actuating rod but besides that she's good to go.
Thank you all for your help and ideas. This is the first time that I have posted on this forum but after this experience I will be much more active.

ok, the truck is failing selftest
what does work, lift/lower, traverse/pivot, steering?

I'm going to take some guesses here. The common problems were the lift valve slamming to one end of it's travel. There is a motor on the end of the valve with a screwdriver slot in the end of it. You can turn the motor with a screwdriver and see the valve move. Center the valve. The valve is on the right side wall of the power unit.

Unplug all the plugs and re install them.

Look for fault lights on any of the cards. There is a box on the platform and the base. Some of the cards are interchangable.

Check your chain slack and chain broken switches. There are four under the seat. I had a few of the chain slack switches go bad.
Check the height encoder. It is on a spool that is spring loaded or retracted. It is basically a very small steel cable that attaches to a switch in the in the base of the truck under the platform. If the cable hangs up and goes slack, it will close the switch and give the wrench light.

I you leave the drive/tow switch in the tow position, you will get a wrench.

These were the common problems. Beyond that, you need the Crown service terminal and book for the terminal.

The wrench light is immediate upon start up - No one in town has any scanner compatible with the unit

The wrench light is immediate upon start up - No one in town has any scanner compatible with the unit

use the traverse or pivot function to build pressure in the brake system.
then key off, wait until it shuts down completely then rekey.
when it boots up see if spanner comes up straight away.
if it does you will need to find out why
if it passes selftest try releasing park brake and see what happens.
let us know either way and we can help further

bad connections at the brake release switch were common. I used to solder in new switches. Your real problem is the wrench light. You need the Crown service terminal and code manual to read the codes. Then you must troubleshoot the code. It has a fault that will not allow you to travel. You can flip the drive/tow switch and release the brakes all day long, but it means nothing until you fix whatever is causing the wrench to come on.

Thank you for the speedy response - we will be out there later today, I'll let you know what we find

I would check the connectors on the main board. I have heard that they loose connection often. I believe they are a replaceable item. I replaced the board on one machine ahd all it was is the connector plug.