I definitely agree with Sidecarbill. It had to have run correctly at least once in its life or Boom would not have been able to sell it. Are these techs from the Boom dealer? I realize that working for the Boom dealer doesn't necessarily mean that they are the sharpest tools in the box, but they should have the best access to Boom for repair info. There are a lot of "box swappers" out there when it comes to electronic /computer problems. There's often no incentive to troubleshoot the problem when electronics are usually not returnable. Try this box....not the fix...too bad, you bought it....how about this box....
Most ECUs have a "limp home" mode. Can you find any information on that?