Also Fairphone Open 16.12 didn't fixed the battery drain bug...
This battery drain bug is very nasty, it is active on all Fairphones with Fairphone Open >= 16.08
On SailfishOS battery drains very quickly, but sometimes also on Android Firmware.
The only possible Workaround is to flash the old Modem Files from this package:
Edit the flash.bat or flash.sh scripts and remove the lines containing aboot, boot, system and recovery.
All other files are modem files and need to be flashed.
Afterwards you will have new Fairphone Open (like 16.12) but with old Modem Files.
There will be no battery drain, but the proxymity sensor will be also uncalibrated.
I don't know, why it is so difficult for the Fairphone Developers to solve this bug, which is persistent since 6 Month!
I don't know, what else should be done, that this bug will be solved?
I provided all the necessary information to the Fairphone Developers but still got no answer.....