Net 4.0 installed and network connectivity). Plug the phone into a PC running a supported version of Windows 10 (with.
Make sure the phone has at least 40% charge, and check Settings, Phone Update to make sure there isn't an update in progress (Windows Phone 8 devices that you reset and turn on will get a Windows Phone 8.1 update and you need to let that run, but put the phone into airplane mode so you don't waste time downloading any other updates).
