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I own a Lenovo notebook (model Z570) on which I have already used a number of Windows and Linux installations pretty well, but now its EFI boot order seems to be broken. After the recent installation of Linux Mint, the notebook refused to react to keys during boot. It still displayed the info text "Press F2 to enter BIOS, press F12 to enter boot menu" but it didn't react when I pressed these buttons.
I decided to investigate this issue from Linux and used efibootmgr, which displayed a boot timeout of 0 seconds. Changing it to 20 seconds worked (and yes, waiting 20 seconds in a splash screen is a bit boring), but this did not enable the keys at boot. Surprisingly, efibootmgr reported boot entries for the EFI setup and the boot menu itself (located as entries 0000 and 0001), which I have seen nowhere else on other machines or the internet. I decided to change the boot order via efibootmgr so that the first boot entry is now the EFI setup itself rather than the DVD-drive.
Unfortunately, the EFI is now unable to save new values for the boot order. This results in the notebook always booting to the EFI setup, and restarting upon exiting it. As the boot order is written to NVRAM, removing the CMOS battery has only reset the clock.
The EFI is a "Phoenix SecureCore Tiano". It does not provide a secureboot-option. Is there an option of altering the NVRAM manually?
Whether EFI setup is stored as a boot menu entry appears to vary between different implementations. Even though most of them are based on the same TianoCore, they still are heavily vendor-customized... – user1686 – 2015-11-05T10:46:14.017