I have a Nokia Lumia 920, well did until it was made into a expensive paper weight.

I upgraded to Windows Phone 10 to check it out, found it was far too buggy to even try out as it wouldn't detect my SIM card after a reboot.
After doing some Googling, I found the downgrade method was to use the  Windows Phone Recovery Tool, unfortunately at the time I didn't come across all the people getting there phones bricked using the same tool.

After installing the tool I ran through the process, everything looked fine. It downloaded the 8.1 image and rebooted my phone to start flashing it, this is where it all turned to custard. A message pops up stating it had lost connection and to do a soft reset using the volume down and power combo and then retry the process again.

This is all good and well however the computer detects the phone as being in Nokia Emergency Connectivity now and the Windows Phone Recovery Tool will not detect it at all. The phone does not respond to and soft reset commands, just a nice black screen of death.

Anyway after much research I find that many many users are facing the same issue from using the Windows Phone Recovery Tool and not just limited to those using it to downgrade there phones.


This quoted from the TechNet forum:

 

"This issue is not exclusive to the Windows Technical Preview, and affects Windows Phone 8.x users as well, including those running 8.1 and devices that have never joined the preview. I personally fall into the latter category, my 521 running 8.1 at the time of the issue.

 

 

 

The issue is with the Windows Phone Recovery Tool and it's method of flashing. In rare cases, for unknown reasons [to users, including me], the flashing process can fail in early stages causing the bootloader to be corrupted and the device to be sent into emergency mode as is normal when the device is corrupted in such a way that it cannot boot. My personal recommendation at this moment is to avoid the Windows Phone Recovery Tool. In the event of necessity to rollback to Windows 8.1 for Windows 10 devices, or to refresh the firmware with a fresh copy for malfunctioning Windows 8.x devices, please use the Nokia Recovery Tool, also known as the Nokia Software Updater, or the Nokia Software Updater for Retail. This is known to work and be safe for flashing devices, and works with any Lumia Phone, permitting your version is up to date."

The main reason for posing here is for some feed back from the local Nokia or Microsoft reps that I know look at these forums.