Well, consider me a freako, but I've never connected it to any FiiO app.
I don't really need to tweak it that much.
So I guess that leaves it as "OFF" in the app.
( :
Regarding my troublesome experience:
After getting "Firmware upgrade finished successfully" and Q15 taking forever to finish updating, I waited for another 2 hours.
Since I had to go out and couldn't leave both the PC and FiiO turned on while I'm away, I took the plunge and decided to disconnect Q15. Nothing happened. Then I turned it off, waited for a little bit and connected it to PC once more.
It turned on, showed "Updating" screen again, though this time, after about 2 minutes, it finally restarted and came back from the dead. Now it's fully working, with v1.82 under the hood.
But I don't think I'll risk updating it anytime soon.