No dash display 2007 Gem

Hi there. A friend has a couple Gem cars. The display doesn’t work in either one. The underhood main controller modules are new in each one. I’m an automotive electronics tech and I’m trying to give him a hand in solving this issue. Is display failure a common issue in these cars? Where would I start in troubleshooting? The connecters are clean and without corrosion.

The display will light up when charging. It does drive. Signal lights work. Headlights. Etc. But, When the key is turned on while charging. They shut off and do not come on at all if not charging.

Thanks for your help!