1991 Toyota Camry What should I look for?

This type of incident could have caused many different problems. It could damage the alternator, computer, the battery.

What I recommend doing is checking the vehicle over to make sure everything is working and the car runs properly. Make sure none of the dash lights are on, all gauges work, the car starts and runs properly. Next, tell the person you want it inspected by an auto electric shop that specializes in electrical repairs. Let him know that he is responsible for any damage that has been caused. My concern for you is that a week from now the computer goes bad or a different expensive repair that was caused by this.