EFI dual boot not seeing Linux on Nitro 5 AN515-51-78C6
Hi there! I have an Acer laptop, Nitro 5, AN515-51-78C6 model. It came with Windows 10 Home. I want to dual boot it with Linux.
I'm using Linux Mint 18.3 Cinnamon, 64-bit. This distribution is EFI friendly and Secure Boot friendly, at least they claim to be.
It booted up from USB stick (and DVD) without a problem. I shrank the size of the NTFS partition, to make room for Linux, and added a Linux ext4 partition. The installation completed OK. The bootloader should have been installed within the "EFI System Partition" that I had selected.
However, nothing seems to have happened. The laptop only boots Windows 10. It isn't giving me the choice of Linux or Windows.
On the Acer screen as it is booting, repeatedly pressing F2 will eventually enter the BIOS, and F12 will eventually enter the boot menu. These work well. However, nothing here is giving me the choice, either. The only boot choice is "Windows Boot Manager".
I tried using various recommended EFI tools to point the selection at Linux instead, such as "efibootmgr" under Linux Mint. I can set the choice to "ubuntu" (the EFI name that Linux Mint installs under, for various reasons). However, this choice doesn't stick, and when rebooting the laptop, it gets forcefully set back to Windows 10.
Changing boot type to "Legacy" instead of "UEFI" kills Windows 10. It can't find itself anymore, so it can't boot. So, looks like I'm stuck with UEFI, or the alternative of reformatting the entire disk under the old MBR way of doing things, and only having Linux, and losing the ability to dual boot.
Anybody else have this problem? Any suggestions?