Test command:
[ -d /sys/firmware/efi ] && echo UEFI || echo BIOS 

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GRUB UEFI not loaded  (https://wiki.archlinux.org/index.php/GRUB#UEFI)
An example of a working EFI:

i5b gerd # efibootmgr -v
BootCurrent: 0001
Timeout: 1 seconds
BootOrder: 0001,0000,0004,0006,0007,0005
Boot0000* GRUB	HD(1,800,32000,7a617bfe-13e7-40ef-960f-3f7d1e74a6d1)File(\EFI\GRUB\GRUBX64.EFI)
Boot0001* linuxmint	HD(1,800,32000,7a617bfe-13e7-40ef-960f-3f7d1e74a6d1)File(\EFI\LINUXMINT\GRUBX64.EFI)
Boot0004* Windows Boot Manager	HD(1,800,32000,7a617bfe-13e7-40ef-960f-3f7d1e74a6d1)File(\EFI\MICROSOFT\BOOT\BOOTMGFW.EFI)..BO
Boot0005  Windows Boot Manager	HD(1,800,32000,7a617bfe-13e7-40ef-960f-3f7d1e74a6d1)File(\EFI\MICROSOFT\BOOT\BOOTMGFW.EFI)WINDOWS.........x...B.C.D.O.B.J.E.C.T.=.{.9.d.e.a.8.6.2.c.-.5.c.d.d.-.4.e.7.0.-.a.c.c.1.-.f.3.2.b.3.4.4.d.4.7.9.5.}...................
Boot0006* Hard Drive 	BIOS(2,0,00)..GO..NO........O.C.r.u.c.i.a.l._.C.T.2.5.6.M.5.5.0.S.S.D.1................>..Gd-.;.A..MQ..L. . . . . . . . .4.1.3.3.E.0.0.0.8.4.B.7.......BO..NO........O.S.T.4.0.0.0.D.M.0.0.0.-.1.F.2.1.6.8................>..Gd-.;.A..MQ..L. . . . . . . . . . . . .3.Z.2.0.C.7.V.5.......BO
Boot0007* CD/DVD Drive 	BIOS(3,0,00)..GO..NO........O.P.I.O.N.E.E.R. .D.V.D.-.R.W. . .D.V.R.-.2.2.1................>..Gd-.;.A..MQ..L.K.M.C.Q.6.1.5.4.3.2.L.W. . . . . . . . .......BO


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