With the init 0 command my laptop did eventually shut down, however, now it only boots into single user mode due to this abomination. Fuck BTRFS. There was NO reason for it to go into its check mode to begin with the previous time when it hung with BTRFS because it had been shut down cleanly. No rebalancing was needed. Rebalancing shouldn't hang the whole fucking system either, nor should it prevent a clean shutdown. Now, thanks to this abomination I can't boot back up. All I ask is a filesystem that can reliably store and retrieve files that can quickly be checked after crashes. BTRFS fits none of these criteria.