Instrument Cluster Poltergeist '91 bmw 525i

Instrument cluster starts out dead, then pegs all instruments and seems to be in a resetting mode. Just put in a new battery. Ok, I’ll admit it, while trying to charge the old battery I miss connected the charger to the wrong terminals. I now have new glasses. My wife says the car now “communicates to her from the dead” with correct information once the car has been driving for awhile. I found this to be true on a highway trip. The instruments totally reset and ran fine after about half hour. Is there a permenant reset for a computer that might fix the problem or is it fried? Driving with no speedometer is making me nervous.

More likely than a “permenent computer reset” you have permenent computer damage. In newer BMW the cluster is a main decision making item in the electrical system along with a GM (general module) the older cars also use a GM but I belive the clusters part is less involved.