I started the GNT650 troubleshooting by validating the power settings in the VP/X Pro. I powered up the panel and all devices powered up including the GTN650. Now I have to troubleshoot an intermittent problem. I then turned off my work light to take a photo and the GPS screen turned off. Turn the work light back on and the screen comes back.
I check the photocell configuration and low and behold, it's set to dim to zero. I changed the minimum dimming setting to 80% and the screen no longer dims to dark. I probably will have to calibrate again for night flying, but there isn't an urgent rush for that.