OSM Not Displaying - 24mh FHD Monitor

[ps540]

**This was the most accurate board I could select when creating this post since there was no board for monitors

I am experiencing an issue with my HP 24mp FHD monitor where I am unable to unlock the On-Screen Menus. During regular usage of the monitor, the following warning message will display: "On-Screen Menus are Locked". After reviewing several posts and user manuals, I have attempted to unlock the menu by holding the menu buttons for 10 seconds and this does not work. I am able to power the monitor on and off with the power button, and can lock/unlock the power button by holding for 10 seconds.

I am attempting to increase the brightness of the monitor and prevent the warning message from displaying.

I have also tried to adjust the brightness from the Windows menu within the OS, and there is no change. Is there a way I can factory reset the monitor without accessing the OSM? I have attempted to unplug the monitor and hold the power button as I read that this could reset it, but still experiencing the same results. 

[Kuroi_Kenshi]

Hi @ps540,

Welcome to the HP Support Community!

Thanks for reaching out!

We're thrilled to have the opportunity to assist you and provide a solution.

I understand your HP 24mh FHD monitor is displaying “On-Screen Menus are Locked” and you are unable to adjust brightness or access the OSM, even after trying standard unlock procedures. Let’s go through a few steps to resolve this.

Verify Menu Lock Method
 - On the 24mh monitor, the menu lock/unlock is different from the power button lock.
 - Press and hold the “Menu” button (not the power button) for 10–15 seconds.
 - If this does not work, proceed to the next step.

Perform a Power Cycle
 - Turn off the monitor and unplug it from the wall outlet.
 - Wait 60 seconds to ensure all residual power is drained.
 - While unplugged, press and hold the power button for 10–15 seconds.
 - Plug the monitor back in and turn it on.

Check for Factory Reset via Button Combination
 - Some HP monitors allow a factory reset without accessing the OSM using a button combination:
  - With the monitor on, press and hold the Menu and Minus (-) buttons simultaneously for about 10–15 seconds.
  - Release when the monitor briefly goes black or shows a reset message.
 - This may reset all settings, including brightness and menu lock.

Adjust Brightness via Windows or Graphics Driver
 - On Windows 10/11, right-click the desktop → Display Settings → Brightness & Color.
 - Alternatively, open your Intel/NVIDIA/AMD graphics control panel and adjust brightness from there.

Check Monitor Firmware / Support
 - Some monitors have firmware updates that can affect OSM behavior.
 - Visit HP 24mh FHD Support and check if a firmware update is available.

Test with Different Cable or Device
 - Try connecting the monitor with HDMI, DisplayPort, or VGA to rule out signal-related issues.
 - Some OSM lock issues can be triggered by intermittent signal detection.

If Issue Persists
 - If the monitor still shows “On-Screen Menus are Locked”, the internal menu lock feature may be stuck due to a hardware/software glitch.
 - A full power reset combined with the button combination usually resolves it.

I hope this helps.

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Best regards,