Just got the lumia 930 a couple of days ago, and it updated to the latest build of winows mobile 8.1. I then downloaded the insider app, and went to get the latest mobile 10 build.
It only gave me an option of fast previews, which i wasnt too worried about, as i have been runnign fast preview builds on my laptop. When I download the update, it fully downloads it, then goes to restart as usual, I get the spinning gears, but the update bar does not move. After a couple of minutes, the phone restarts, but it goes straight to the screen which shows the low battery, charging only icon (even though its fully charged). It then tries to start up again when it thinks it has enough charge (even though its fully charged), and goes back round again, switiching off before the progress bar even starts moving.
It will keep doing this for some time, and I managed to do a soft reset so that the phone is usable again but just wondered if you were aware of this issue? The build number is 10.0.12648.133.