Have you checked the outlet, where the wire connects to the back? It might have just come loose.
In terms of cost, electrical problems are hit and miss. They can be easy to solve, or they can take hours, which drives the cost of labor up. You just can’t predict what it will cost to solve an electrical problem. Sometimes, you pay for the labor to do troubleshooting, but drive away with the problem unsolved. Electrical problems can be a gamble.