Guys, please, just read my simple instruction and do not ask stupid questions!
1. Flash CMJ1 ATO with official CSC-file (or unofficial, it's not important).
2. Simply update to WP8.1 with the latest 15.3.2 firmware.
3. Optionally you can do hard reset after update.
5. By using CustomPFD (or other registry editor) pretend Lumia (I pretend RM-1040_1021).
4. Go to the Windows Insider and choose fast ring.
5. Update phone to the Windows 10.
6. IT'S NECESSARY to do hard reset.
СMJ1 is version of GDR3 firmware, you can download it
in my archive.
ATO is CSC of Austria (I could be wrong, but it does not matter). This is CSC gets all updated almost always at first.
With CMJ1+ATO you will get ALL latest updates for our phone, specifically 8.10.14157 and f/w 2424.15.3.2. It's firmware solved ALL problems and bugs!
ALL! Boot loops, camera bug, Bluetooth bug, etc.