The old backups will be accessible.......IF.......the hard drive is not damaged.
We're going to start all over.
Connect the Ethernet cable from an Ethernet port on the Velop router to the WAN "O" port on the TC
Power up the TC if it is not already on
Hold in the reset button on the back of the TC for 7-8 seconds and release
Allow a full minute for the TC to restart to a slow blinking amber light status
Click on the WiFi menu at the top of the Mac's screen
Look for a listing of New AirPort Base Station
Click on Time Capsule, or it might say AirPort Time Capsule

That will start up the setup "wizard". The wizard will take a few seconds to analyze things and then suggest that you set up the TC to create a network. That is the correct setting. We will turn off the WiiFi on the TC later. The window will look something like this, except that you will see a Time Capsule displayed.

Network Name......Type in anything that you want, but not the same name as the Velop network. Later, the network will be turned off after some checks
Base Station Name.....Type in a device name that you want to call the TC. You can use the same name that you used before if you wish
Password.....Type in a password for the TC
Verify.....Type in the same password again to confirm
Click Next and the setup wizard will automatically apply the correct settings for the TC......(including Bridge Mode).
After a minute, there should be a green light on the TC
Close the AirPort Utility window
Now make sure that you are logged onto the Velop WiFi network......not the TC wireless network
Open AirPort Utility again on the Mac and the TC should appear
Does it?
If yes, click to select the TC, then click Edit
Click on the Wireless tab at the top of the next window
Change the setting for Network Mode from Create a wireless network to Off
Click Update and let the TC restart

Post back on your progress.