Cannot boot to bios after fw update
This computer was running Arch Linux without fwupd installed. I installed KDE Neon (an ubuntu base distribution). it installed "secure boot dbx update". Now I cannot enter the bios again with DEL, F2, or ESC. systemctl reboot --firmware-setup says "cannot indicate to efi to boot into setup mode firmware does not support boot into firmware".
I've been booting to bios since I got this machine in ~2016. This is essentially disastrous. Fortunately I am still able to boot KDE neon so I still have a working computer for now.
Any idea how to fix this?