Static sound from only one speaker

My car was at the mechanic for over 3 months while they went back and forth with the extended warranty company. It had a lot of work done, especially with the engine. But it was off for the majority of those 3 months. I got it back but there's a static sound that starts about 4 seconds after turning the car on(with or without the engine). It doesnt matter if the head unit is off. And its coming through only one speaker. Any ideas?