Crackle on playback

Slightly confused by the driver thing, as the only drivers I have ever installed are the ones downloaded yesterday from this website (indeed, I was a bit confused when the version shown in the Mixer App didn’t match what I’d downloaded!).
More importantly though – I tried the firmware update and it didn’t work. User manual says to check on the website for instructions but couldn’t find those, so did the obvious and launched the executable, with the LR-16 plugged into my USB.
The unit’s screen showed “Firmware Upgrade: Do not switch off!”, but then stayed like that even after the program looked to have finished running. I left it for at least 10 minutes to be sure. Then I clicked “update” again in the application and received the message, “update failed; error code Ox2e (or maybe 0x2e)”.
Tried a second time, with the same result.