/dev/sda is the whole disk, if it is partitioned it won't work.
/dev/sdb is most likely what you are installing from, such as a pendrive.
]]>You might be missing a grub config. It happened to me on another distro. Sometimes grub doesn't detect the linux kernel, just the BIOS, so it only makes a menu entry to enter the BIOS when you boot up! So you just needed to edit the grub.cfg probably, or let it try to generate a new config when you tried a second time.
As for why?? I can't say I know yet, still learning lol
]]>What's wrong?
I finally enter grub menu successfully after I change the init to openRC. And that question didn't appear.
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