unetbootin rendered system unbootable

[lejeczek]

hi everyone

I've run unetbootin to installed freeDos on a usb stick, 
which it did, but now my system does not boot. Gee..

I have a fedora27 on a Dell laptop in EFI mode.
System attempts to boot, where it should do it waits just a 
few sec and says no bootable devices available, or something 
like that.

I boot a liveCD fedora, there I do:
# efibootmgr -v
...
Boot0008* f25 
PciRoot(9x)/Pci(0x17,0x0)/EDD10(0x2a010480)/HD(1,GPT,c9b2adc2-.....,0x800x0x64000/File(\EFI\fedora\grubx64.efi)
...

that entry above was, should be my fedora installation. I do:
# fdisk -l /dev/sda
...
Device....
/dev/sda1    2048    411647    4009600    200M EFI System
/dev/sda2    411648    1435647    1024000    500M Linux 
filesystem
/dev/sda3    1435648    5000117503    49...    237.8G Linux 
filesystem

So it seems like everything is there, right? I'm really 
asking, I'm a novice here on grub2/efi subject.

I tried mounting /dev/sda1 under /mnt in live fedora, then I 
did:
# grub2-install --efi-directory=/mnt/EFI /dev/sda
which command said id did without errors, but all I can see 
happened a new entry was added which efibootmgr would show, 
but that new boot id would not boot also.

Any help, advice on how to troubleshoot it I'd greatly!! 
appreciate.

many! thank, L.