I just wanted to state that I pretty much have had the same issue. I recently built my new PC (11/19/2021) and the first few days things worked great. I was able to change what was displayed on the LCD screen and customize it as I liked. Then, one day upon a restart, I got the Red ! on the screen. I was able to restart and the screen appeared to go back to working. I don't think it actually did as now, the screen will show an image of the Liquid Temp but its frozen. The image normally has swirling lines around the border that are now static and the temp is always 31. I can no longer see the options within iCUE to change anything about what the screen displays. Not sure if there was an update to iCUE at some point and that's what killed it but the screen is now currently useless unless I can find a solution to why its stuck with a frozen image.