For the many that have had issues with the Over the Air (OTA) download for firmware image 39-5 bricking their devices the saviour is here:
The N950 firmware version 39-5, previously released as an over-the-air update, is now also available as a flashable image.
The provided OneClickFlasher can be used to return the device to a known functional state after some bit-too-careless late-night hacking, or if a previous over-the-air update has failed for some reason.
To download the image and read the installation instructions, go to the following page:Nokia N950 OneClickFlasher for Firmware Version 39-5
Refer to the release notes to find out further details about the new firmware version.
Source N9 Developer