HI Gabriel
If the backup switch stopped working it could mostly be due to file system corrouption.
Once you poweroff/poweron the backup and if it comes back up then check in the console logs for any bad blocks etc... during the boot up of backup.
Also you can check for the logs /var/run/dmesg.detail file to confirm if there were bad blocks. Usually a power cycle will fix it and you may not see it.
Hope this helps
Thanks