Speedometer Quit

The speedometer would work sometimes, then, if I went over something real bumpy, or took a fast corner, the needle would start floating, showing thirty or forty mph. And it would continue floating, up to sixty, seventy and eighty mph (even when I might be doing about twenty!). Then we found if we disconnected the battery cable, and reconnected it, the speedometer would sort of reset itself and work again. Also, the check engine light used to come on when this problem started and the code said, "rear wheel speed sensor". But the last couple of months, the check engine lite has stayed off, while the problem has continued. One day, after taking a fast corner, the car lost total power, stopped in the roadway, the gauges all went spinning, and the radio shut off. I put it in park, then started it. It ran, and car continues to run, but the speedometer needle now sits at 'zero' and wont move. We looked under the hood and found the bracket holding the battery was broken and part of the metal bracket had touched the positive battery post causing a burnt area and possibly a momentary short. My question: do you think it is the wheel speed sensors still? Or could it be the "cluster" on the dash board, or did something else happen? Since the problem started before the battery issue. I am confused as to what the problem is. I do not want to throw parts at the car. Please advise. Thanks so much.