HP Z420 will not boot after turning on Secure Boot in BIOS

[Pugpal2]

Trying to get my Hp Z420  win 10 pro 64 bit with Intel Zion 1620 cpu ready for Win 11,  I turned on TPM 1.2  which worked and said it was ready. Next I turned Secure Boot on in BIOS … on power up the PC gives 6 beeps and 6 red flashes by pwr button and no boot!

How to recover from this? Thanks.

[Paul_Tikkanen]

The error code has something to do with the graphics.

Assuming you have Windows installed in UEFI mode, the graphics card you may have installed is having a problem with secure boot--especially if it was not one of the supported graphics cards HP offered in the model series.

4AA4-0128ENUC.pdf (hp.com)

The z420 model series does not natively support W11 as none of the processors meet the W11 hardware specs.

Windows processor requirements Windows 11 supported Intel processors | Microsoft Learn

If you are interested in installing W11 on your PC as is, you can read this discussion for how I upgraded several HP and Dell notebook and desktop PC's that did not meet the W11 hardware requirements to W11 22H2/22H3.

You have to use the version of the Rufus utility that I zipped up and attached in the discussion (v3.18).

Re: Issues upgrading to windows 11 - HP Support Community - 8517912

If the in-place upgrade fails, you should be able to clean install W11 using the bootable W11 installation flash drive you made with Rufus.

[Pugpal2]

Is there a way to revert to original BIOS setting and remove secure boot? 

[Paul_Tikkanen]

The only way I know of since you can't access the BIOS settings would be to clear the CMOS.

See chapter 5, page 155 of the service manual:

c04205252.pdf (hp.com)

[Pugpal2]

Is there a way to revert to original BIOS setting and remove secure boot in BIOS setting? How to get back into BIOS setting? 

[Paul_Tikkanen · Accepted solution]

I've already indicated what your only option is unless you want to try removing the graphics card so you can get into the BIOS and use the onboard Intel graphics so you can disable secure boot.

[Pugpal2]

Thanks for your help. I did remove the Nvidia Quadro 600 card but it still would not boot into BIOS. however after clearing the CMOS as a last ditch attempt to recover, it did boot into the BIOS... and I was able to disable the Secure Boot. Checked date and time and it retained correct values.

Now on power up  the win logo comes up and a circle of dots ... message"Attempting repairs. " It now asked me to Reset this  PC. Which I did. 

[Pugpal2]

Thanks clear CMOS button was the trick! Thanks.

[Paul_Tikkanen]

You're very welcome. 

Now you can install W11 if you still want to using the method I posted.