When my 520 "broke" I was getting 80188308 code. And had a failure to load 8.1. At the time I had something like 2plus GB space available memory of the 8GB.
Plus 64GB SD card with 16 plus used for music. So I did hard reset and things went downhill from there. Gears then :-( then having to do the Nokia thing.
I'm guessing my problem came about because of lack of space in the internal memory. Cause after the going to Nokia website and doing the restore I got to 4GB of free space.
And the update to 8.1 went fine and the and both (problem child) 520 and 920 have been working great.
I'm wondering what going happen with hardware design for it.