to recover on a btrfs Filesystem you have to do follow simple steps

• Boot into your last working snapshot
• mount |grep 'subvol='
• # keep in your mind 'X' means your drive
mount /dev/sdX -o subvol=/ /mnt
• # we remove the '@' by
mv /mnt/@ /mnt /@_old
• # now we will recover the snapshot to our root-file-system.
# Keep in your mind to replace 'X' with your snapshot number
btrfs subvolume snapshot /mnt/@.snapshots/X/snapshot /mnt/@
• reboot

That’s all.