2001 Subaru Outback Idiots lights on car

My recently purchased second hand subaru started leaking fluid from the head gasket. There was a recall on that area. I did not drive the car for 2 solid weeks until its repair date. When I put it in gear, the brakes had "frozen", but released. They sounded "grindy" at first, but gradually got better. The brake light had come on though and was on for about 6 miles. Then, the abs light came on, and the needles for the speedometer and rpm started jumping. The jumping stopped, the brake light went out, and then the abs light went out. During that time the car drove normally. I only had to go another 1/4 mile. At the repair shop, they did the recall work which included rustproofinng the underside rear carraige, and putting a powder into the radiator that would seal leaks once it was run for a while. I picked up the car to drive home. On the drive, the brake light was on and then a mile later the battery light came on, and then the abs light came on. Again, the car seemed to drive normally, but all 3 lights stayed on until home. At home, I checked the alternator belts, and they were there. I restarted the car, all 3 lights came on, and the wheel on the alternator was turning. The lights also worked. Any suggestions