this is for hardriders posts only.....
all you other guys should have started a new thread for your issues to help keep confusion to a minimum...
I'll be more than happy to assist in the other issues if done so..
but for now hardrider only....
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codes C0 through CE indicate a fault in the internal system software. (the TMM) This fault should never occur. Contact Material Handling Associates if this problem is observed.

This is what manual says about this series of codes and thier only solution is to replace the Vehicle Manager.

Now since you had issues with the control handle and had that worked on and immediatly had issues and the tech came out and replaced the carriage board for some reason, the only thing that comes to mind now is that during that process someone inadvertantly may have shorted circuits and burned something in the TMM.
I have worked on many of these handle assy's and i can tell you from first hand experience that they are VERY tedious to work on, reassembly HAS TO BE PERFECT or wires will get pinched or alignment pins can get broken and the handle will not assemble correctly and create a whole mess of problems that will run you around in circles. Alot of what you described in previous posts after your initial handle repair.
And for anyone thats listening, for future reference, you do not use OHMS to calibrate the potentiometers, it operates off of voltage ranges to determine what its functions will do. You can successfully setup a pot using the maintenance menu and can be done easily if you know what to do and what mode to set it in while in there. And what most dont realize is that you have to be in the setup mode BEFORE you even start to do the replacement or you will NEVER get into the setup menu's after the part replacement.

Being the handle connects directly to the TMM i think it would be safe to say that this scenario may have burned something in the carriage board, hence why the tech replaced it but it may have also fried something in the TMM as well.

Seeing that problems keep cropping up if it were me i would go back to the control handle and recheck it and make sure there are no pinched wires. As for the TMM , you can dissassemble it and check the components in it and see which one is damaged if it is indeed burned somewhere. The TMM has 3 components, a power card, the serial board interface and the logic board which mounts directly onto the serial board.

You can replace the complete TMM if you like but that is VERY costly compared to just replacing the component that is damaged. So by all means have your 'professional cat dealer' do the work. Hopefully he will be proficient in these trucks and be able to determine what is exactly wrong and repair it.