I've just had a bit of a scare with efibootmgr -c. My laptop
(Entroware Aether/Clevo N750BU) wouldn't boot past the first splash screen.
(Before give getting the boot menu)
I assume it's actually a bug in the laptops UEFI when parsing the entry, I
might have had the issue with -C as well (not adding it to the
boot order). But I think the issue was compounded due to it being the
first entry. I thought I was done for, it was bricked.
But it wasn't, I removed the SSD and I started to get an error message
instead of a crash on boot. So I booted from a flash drive and deleted the
entry with efibootmgr, reattached the SSD and everything
booted fine.
The crash was only occoring when the drive that the entry pointed to was connected, and luckly not when it was being parsed without the drive.