If the fault is still there this evening, switch the battery off and unplug the display unit to see if it makes any difference.
If the motor runs properly with the display unplugged, switch off the battery and plug the display back in and then switch the battery back on again.
If the motor works properly each time the display is disconnected
(but not when the display is plugged in) there must be a fault within either the display unit or its wiring/connector.
If the controller still won't work with the display unit disconnected, the problem is likely to be either within the controller itself or somewhere within the motor wiring harness.
It is also worth checking all wiring and connectors to ensure everything is properly connected and also to check that none of the wiring has been damaged by either chaffing against
(or being trapped by) any of the moving parts such as wheels, tyres, pedals, chain, steering and suspension etc..
I would also suggest thoroughly checking the four unused wires on the short unterminated cable coming from the motor harness
(shown in the lower right corner of the diagram below), if the insulation on the individual wires has shrunk in the extreme temperatures the copper wires can touch against each other causing a short circuit.
If the Red +5v wire is touching the Black ground wire it might explain the communication error and this would also prevent the throttle from working.
I also recommend that you closely inspect the unused wires for the horn and headlamp as well to ensure nothing is likely to touch together and cause a short circuit there.
Alan