Hello all. Opened up the pool today and turned on the filter. My Pool Pilot 7500 has a blank screen and flashing red system light. I checked all connections and fuses. Checked the button battery for charge and contact. I see the control board 75003 837N is $500-600. Is there any way to test/confirm/troubleshoot the board to make sure it actually needs replacing before I drop the $$$. Not so clear but in the pic attached, there is a dark (carbon?) spot in the top/left (bottom/left when installed) display window.
Thanks for ant suggestions.

Thanks for ant suggestions.
