'90' Instrument panel problem

[kmillar]

I think this problem started after my original battery went dead, I boosted the old battery back into life, the car drove okay but the LCD screen would scramble itself, then right away it would read normally. I changed out the battery for a new Delco unit and have pulled the CCM codes on Module 1, segment 1, no error codes are present. Only code that comes up is C12, which is normal, I believe.
I think my next course of action is to check the ground at G201, which I believe is by the drivers kickpanel. Other than pulling the cluster, does anyone have any words of wisdom? Any help would be appreciated.