Recover data from a secondary disk

This is the story, I have a lenovo laptop running the latest Qubes. My laptop has two encrypted disks, one ssd and one hdd. There is a backup qube that stores all the backup from active vm in the primary ssd on hdd. Today my laptop fell on the ground from a one meter high desk. The ssd broke and I could not read anything from it, but miraculously the hdd seems intact and still works. The problem is I have no idea how to extract data stored in the backup qube in the hdd.
The secondary disk is added according to this tutorial
I have searched some qubes disaster recovery tutorial but they are not very helpful. This one requires direct access to the backup file, but when I tried to decrypt my secondary hdd on other linux host I only got a bunch of lvm which I did not know how to handle them. I know there is definitely a way to extract data out, but it seems the file system of qubes is quite complicated and I did not understand how it works. Could anybody help me? Thanks for your help

If you have an extra drive available for a fresh installation of Qubes, then the matter comes down to getting your backup HDD recognized by your newly installed system.

Just as a warning, though, through out the process, you need to be careful not to accidentally wipe out your backup HDD so perhaps you should detach your backup HDD until the installation is complete. Also, after the installation, don’t try any “cryptsetup luksFormat” type of command that will format your backup HDD.

During the installation, you should use the same luks password as your backup HDD for your new drive to avoid a second password prompt at boot.

Once installed and your backup HDD attached, I think simply running those three lines below would do it.

Once your system recognizes the VM, saved on your backup HDD, start the VM and then go to Application -> System Tools -> Restore Backup.