You're correct: The backup/restore function only applies to pi-star configuration settings (and omits certain ones such as system/dashboard passwords).

It does not back up the entire card.

There is a way to make a complete, fully functional, backup clone of your existing Pi-Star installation to another microSD card.  Doing so allows you to power down your hotspot, swap in the cloned copy for the corrupted one, power up the hotspot, and be "back in business" in no time.

Check here for details: http://mitchhopto.com/rpi-clone.html

Of course, you need to do this BEFORE you corrupt your only copy.  Unfortunately, it sounds like you're past that point.  But keep it handy for when you manage to get it running again.

73,
Joe, WB3IHY