A newly found bug in the recently released Windows 10 Mobile preview build 14267 has caused Microsoft to ask that owners of the Lumia 550 smartphone who are signed up for the Insider preview program to not get that build.
Microsoft's Gabriel Aul has updated his original blog post with this additional note. It offers a workaround for this problem for Lumia 550 owners who have encountered this bug:
"Several Windows Insiders with a Lumia 550 have reported an issue where their phone no longer charges or connects via USB after upgrading to Build 14267. If you have a Lumia 550, we recommend holding off going to this build. If you have hit this issue we recommend rolling back to Build 10586 using the Windows Device Recovery Tool. You will need to connect your phone to your PC via USB first, open the Windows Device Recovery Tool and choose "My device was not detected", choose "Lumia" and turn off your phone and let it reboot in order for the Windows Device Recovery Tool to detect your phone and reinstall. "
"If you need to download the image, your phone may reboot back into the OS, once the image finishing downloading completely – reboot your phone again and it should begin reinstalling Windows 10 Mobile. If your Lumia 550 is really low on battery, switch your phone into flashing mode by turning your phone off first and press power button and then volume up until you see a lightning bolt on your phone's screen. This will allow your Lumia 550 to charge. You should let it charge a bit before using the Windows Device Recovery Tool to roll back to Build 10586."