Beware - the upgrade process to v1.82 most likely bricked my Q15.
At first it seemed to go well, but at around 70% it showed some kind of an error (stupid me for not saving any screenshot) and asked to disconnect the device, turn it off, then turn it back on, reconnect it and run the update once more.
So I did just like it said - disconnected Q15, turned it off and then turned it on.
Well, Q15 booted just fine, it showed its default USB PCM screen, it remained responsive to the buttons and the volume wheel, I could go into the settings, change input mode, but it couldn't be recognized by Windows or my Mac Studio.
The update tool on my Windows PC told me that no device was connected.
Well, what to do?
I tried giving the internal 'Factory Reset' a go, since, like I mentioned, Q15 acts like nothing really happened and I could go into its settings.
After resetting, the device turned itself on and showed "Updating" on the screen. I left it for over half an hour but nothing happened.
I ran the update tool once more and, thankfully, this time it recognized the Q15 and was able to successfully flash the firmware, at least that's what it said - "Firmware upgrade finished successfully".
During the whole time Q15 showed "Updating" on the screen and it's been like this for the last forty minutes. Still hanging with this "Updating" info.
I don't dare to disconnect the USB cable once more, but I'm not sure what to.
The battery was charged to 100% and the device was connected to a separate PD charger, PEQ was set to 'OFF' and UAC 2.0 was enabled.
I followed all the steps and didn't experience any problems last time when I updated it to v1.66
@FiiO , any way to fix it myself?