bttt
I found a very similar post to someone that had the same problem:

W810 mess up - Top Sony Forums

It sounds like it is most likely the gdfs. I think I'll give it a try since I really have nothing to lose at this point. Anyway, under Top Sony Forums > Downloads > GDFS, what's the difference between .bin, .gdf, .sbn? In other words, will I need all 3?