Geo prizm 1994 Radio Err9

Hi
I have Geo prizm 1994. The car didn't work ebout 3 month. Battery was turn-off. Now when I change battery, radio show Err9.
Help me.
Miron

P.S. Sorry for my english

Considering a Geo is not a Chevy pickup, I would post this in the GEO section.

You haven't heard of the new Geo prizim Silverado 4WD?

I didn't know that they made them in '94 though. I am pretty sure '95 was the first year of production.

I could be wrong though!