car started making noise and check engine light came on after new belt

Hey, I have a 2008 manual subaru impreza. In the last couple weeks the serpentine belt was making a lot of noise and was clearly time to be replaced. 3 days ago a friend of mine came around and replaced the belt for me. Looking at how the old one you could tell it was well worn. While lifting the alternator back into place to tighten the belt the bracket snapped. This seemed to have no impact as we were able to lift the alternator into place and tighten the belt perfeclty. There was no movement in the alternator even with half the bracket moving. Later that night I went to take the car for a drive and the check engine light came on, the traction control came on and the cruise control was flashing. There was a very strange noise coming from the engine and had no idea what it was. I quickly turn back home as I didn't want to try the car in that condition. the next day I started the car and the same issue, I checked around the belt and saw the power steering pump was covered in fluid. However, Last night I started it again and the lights were off and there was no noises coming from the car and it was running perfectly. The alternator never moved and the belt kept tension

Really confused about what this could be