Please Help....ABS

[PAPABEAR76058]

My Son turned My Truck off Sat. But the radio was still on. (I wired it that way). Tuesday come's around and of course the battery's r dead. I charged them up and reset the computer. And I also unplugged the abs thing on the rear pumpkin. When I start it. the abs light goes off but comes right back on and say's on. Never had a problem till I let the battery's go dead. Thanks in advance