if u stay on

<grub rescue>
//if u got the "grub>" prompt so move over to STEP 2
** STEP 1 **
//find disks
ls
//output like
(hd0),(hd0,gpt1),(hd0,gpt2)....
//try to ls hd0
ls hd0
//u got an output about partitions keep an eye on btrfs
//in this example its (hd0,gpt1)
ls (hd0,gpt1)/
//output be like 
// @, @/root, ....
//now we have to setup the grub

grub rescue> set root(hd0,gpt1)
grub rescue> set prefix=(hd0,gpt1)/@/boot/grub
grub rescue> insmod normal
grub rescue> normal
//grub boots into the normal mode

** STEP 2 **
//check the enviroment vars
grub> set

// now we setup the needed settings
grub> insmod part_msdos
grub> insmod btrfs
grub> insmod {gzio|xzio|lzopio|??}

// if not working... try insmod gzio; insmod xzio... and so on.
grub> set root=(hd0,gpt2)

// now wee need to find out the boot UUID so we read the fstab file
grub> cat /@/etc/fstab
// find the UUID for the / 

grub> linux /@/boot/vmlinux-'(Your VMLinuz-File)' root=UUID='(Your ROOT / UUID)' rw rootflags=subvol=@ 

grub> initrd /@/boot/initrd.img-'(Your INITRD IMAGE FILE)' 
grub> boot

// now sit back and cross your finger, and watch your OS boots again. 
// after sucessfull boot u have to update your UEFI enviroment. 
// start a console with root access

#>efibootmgr -v
//check ur root HDD 

#> mount 
//keep an eye for your boot drive in this case /dev/sda 
// Setup a new UEFI ENTRI for ur Vendor like debian, Ubuntu ... 

#> grub-install --bootloader-id (YOUR VENDOR) /dev/sda
//Check the UEFI Bootmanager again..

#> efibootmgr -v 
// now we need to install the GRUB Bootloader 
#> update-grub

//or
#> update-grub2

#>init 6
// for reboot an now ur system boots again