So I hooked up a new head unit in my car today. When I was hooking the battery back up it sparked a few times pretty good... I turn over the key. Car starts(rough) head unit works fine but the amps won't turn on and the trunk release won't work. Then when I started the car the check engine light was on so I scanned and got a p0107 code. It's definitely from low voltage somewhere... Just not sure how to fix the no amp issue and y woukd the code pop up.