HP Z4 G4 Workstation locked up when swiched from secure mode to legacy

[Anjum01]

I wanted to boot into legacy mode from secure boot, once I made the change did not knew that there were some keys need to be input once you save and reboot, now the system would not past post you can press Esc and F10 key but the system just stays on that screen and wont past, I don't know how to reset bios in any other way. I have tried presing the clear cmos button on the system board and also on the back but nothing happens. Tried to get with HP Support but they were not able to help me. Please help. Thanks.

[Bill_To]

Hi

The only other option I can think of is to remove the CR2032 MB battery when the PC is off and disconnected from AC power.

Depress and hold down the power button to drain residual power from the MB before removing this battery.

Remove the MB battery. Wait for about 5 minutes then reinstall the MB battery.

Try to start the PC again.

[Anjum01 · Accepted solution]

Thanks Bill,

I already tried that as well, but what I did finally to get it working again was:

Plugged a p/s2 keyboard, removed all the M2 drives, PCI M2, disconnected SATA HDD, and only left 1 M2 connected to the MB. Finally, the unit reset itself and then gave me all the prompts that the system was reset, and the date and time was reset etc. Switched back to secure mode, and plugged the removed hardware back in.

When will have time will try to mess around with legacy bios settings. Thanks again for your reply. Cheers!

[Bill_To]

Hi @Anjum01 

My pleasure.

Interesting solution. Have never seen a CMOS reset accomplished by removing devices.

Would guess removing the system disk cleared the pending switch to Legacy operation.