Background: I have a Dell T5810 with BIOS A34. It works fine with UEFI. However, I have recently enabled Secure Boot. This turns out to disable my graphics card (an Asus GeForce GTX 1050 Ti), presumably because its firmware isn't compatible with Secure Boot. Since the workstation doesn't have built-in graphics, I now have no display. The system does boot; I can still access its Linux install remotely, but the main display remains blank at all times, even while booting. It leaves me in a catch 22 that I can't just disable Secure Boot again, because I can't see the BIOS menu anymore! Others have run into this issue before.

My options to disable Secure Boot without a display seem to be:

• Reset the BIOS NVRAM on the motherboard -- doesn't work for me (with the battery technique).
• Temporarily install a different graphics card -- unfortunately, I don't have one readily available...

Based on online videos of people navigating the BIOS, I have now tried to disable Secure Boot blindly, with the keyboard:

• Repeatedly tap F2 (to get into the BIOS, around the time NumLock lights up)
• 8 x ArrowDown (to get to the "Secure Boot" entry, would be 9 x on a laptop with an additional "Battery" entry)
• Enter (to expand the entry)
• 1 x ArrownDown (to get to the "Secure Boot Enable" entry)
• Enter (to enter the Secure Boot panel?)
• Enter (to select "Disable"?)
• Enter (to confirm "Yes" in the popup)
• Esc (to exit the BIOS)
• Enter (to confirm "Yes" in the popup and save the changes)

This sequence and many variations with SpaceBar and Tab don't seem to work. Esc mostly reboots right away, suggesting I haven't changed any settings.

After a couple of days, I'm running out of ideas. Can someone with a functional display provide a working key sequence to disable Secure Boot? Thanks!