When a backup restoration in cPanel goes wrong, it can get be aborted or have the process killed but still show restoring backup in the restoration queue.
This is causing by the backup restore manager still having the job in the queue.
To resolve this and flush the backup queue start by killing the backup process or attempting to abort it in WHM.
Once this is done use the following steps to empty the backup queue.
Once the restore queue has been removed, you can update the restore manager with the following command: