I was following this guide to setup extroot on a external USB drive.
In step 4, Transferring data,
Right after I did mount ${DEVICE} /mnt, I did reboot by mistake without entering the "tar ..." command.
The modem (Archer C7) now can no longer boot up properly (I don't see wifi SSID anymore.)
Is there anyway to recove from this? I suppose the reason it failed to boot because the mount point no longer exists in the system?
I finally got the chance to look into this issue.
Apparently, the FW reset itself and I am able to log in using wired connection. All configuration has been wiped. Bummer.