I really don't recommend just taping up the wires for the handle if some were exposed. Replacing that harness is your best bet otherwise in a few weeks you'll have the same issue again or one of the PCB board will short out if the wires make contact with the handle or tiller arm.

I recommend looking at the brake switches on the knuckle, the wires sometimes get pulled when turning in one direction or the other causing it to momentarily close the brake causing the return grip message. I would also check to make sure that the brake switch is closed for the full range of motion of the tiller arm as sometimes there can be a dead zone that momentarily opens one of the switches.