Frigidaire upright freezer model LFFH21F7HWJ

Went dead during a lightning storm and would not run no matter what i tried. I bought a new display for it and it runs and cools, but the display only shows 88 High Temp and not the inside temperature.

The old one i removed did the same thing but would not turn on the freezer.

So, i replaced the thermistor and have the same issue, but it runs now. inside temp is down to 20 degrees (using a digital temperature)

My questions are 1. did i get a bad display board? 2. is something else causing the display to show 88?

the control board is #299366300. should i buy another one? No one accepts returns once i buy one. ugh

and suggestions would be welcomed!!!