There are three typical damages:
- blown FEts - shorted phase wires or too much load - easy repair
- damaged 5V supply - shorted signal/hall wires - fairly easy repair
- damaged logical circuits inside - usually water damage, especially when you ride on salty roads in winter - difficult to diagnose and repair
When you suspecting water damage it might be not worth sending it to repair, if not is probably wort time and effort.