Btrfs snapshot rollback problems

I installed using Manjaro Architect and chose btrfs, then I set up grub-btrfs and snapper. I have the snapshots subvolume mounted at /.snapshots, and various other subvolumes of the root subvolume (I can give a more detailed explanation of needed). In the middle of a system update (sudo pac-man -Syu), for unreasonable reasons, I rebooted, and the system wouldn’t boot. It showed the option to boot from a snapshot, but when I chose a kernel to boot, it just hung on a blank screen for over an hour on two different attempts. So I booked from a USB with Manjaro KDE, then did this:

  • mount /dev/sda2 /mnt
  • cd /mnt
  • mv @ @.broken
  • btrfs subvol snapshot /@.broken/.snapshots/242/snapshot @

Based on advice at wiki.archlinux /Snapper#Restoring_/to_a_previous_snapshot_of@

Now I can boot the system and use it, but I can’t delete @.broken because it’s still linked to all the subvolumes (such as my home directory subvolume, which I don’t want to delete), and snapper and grub-btrfs aren’t working.

Any hints?

Thanks in advance