Monitor Stuck on Dead Pixel Test?

If your monitor is stuck in color cycle mode and you cannot access the menu settings, try power cycling the monitor by turning it off, unplugging it, waiting a few minutes, and then plugging it back in. Check the physical buttons on the monitor to ensure none are stuck. If available, use the monitor's reset function or consult the user manual for instructions. Try disconnecting and reconnecting the video cable. Additionally, you can use a Dead Pixel Test tool, available online, to check for any pixel-related issues, such as stuck or dead pixels, which may be affecting the color cycle mode on your monitor. If the issue persists, test the monitor on a different computer. Contact the manufacturer's support or seek professional assistance if the problem persists.

J'ai des lignes sur mon écran.

I recently bought an old used HP monitor which upon receiving had the same issue. Since nothing worked to get it unstuck from this self-diagnostic mode I finally decided to dive in and dissasemble the monitor. I physically unplugged all important internal cables (PSU, motherboard; control panel with buttons) and let it sit like this for a couple of minutes so every component discharged properly. After reasembly and connecting to PC it finally gave picture. Also, to prevent future issues, I disabled sleep mode via OSD since I read that it can cause this issue during power surges. Seems like sometimes the only solution is to do a proper hard reset like this.