Then, it looks like that problem is relevant to MCU/display_controller (I'm not sure whether the devece's display is controlled by MCU or has the build in controller) and I'm afraid that there will be a need to send device to manufacturer to replace it according to their warranty statements. If this will happen I would advocate to move (somehow) your stash to new addresses not related with your SEED on Cold Card Q (before sending device to manufacturer).
I don't think the issue is MCU or display controller or LCD at first boot it shows verifying..... and then suddenly black screen and stuck without any signs of reading the SD card and the red light is not blinking and it quickly turn to green light it stucks on verifying there's something on that part corrupted.
What I suspected it was just a software issue related to flash memory that needed to be cleaned and flashed with clean firmware but Coldcard support or documentation does not have a clear method to fully flash the unit. I'm sure coldcard devs have a unique flashing method they don't just want it public. Look at those repair center for devices like phones they have a software tools that is not open for public but can able to fix most of the software issues.