It might be shorted out further down. If you can dig down to the board so the individual wires are separated, you could use a voltmeter to measure the lines. The controller has to be powered up with display attached to test. Motor can be disconnected. With nothing connected, you should see something like 4.3v on both the 4.3 wire and the speed wire measured against ground. Also check continuity from the ground wire to the main battery negative. If the voltages are OK then it will probably work. Speed wire might be 5v.
If there is a damaged spot in the cable, the best thing is to cut that part out completely and shorten the cable.
If any of the wires made contact with the pack voltage wire in the cable, it's probably toast. If the input to the MCU got pack voltage, it will blow that input and destroy the MCU, which is not replaceable.