After upgrading to android 7 (from the link posted here) and having all the problems stated in my posts I have decided to flash the phone via local update to android 6 (update file from a link posted by admin). After the update the phone entered in some restarting loop so I flashed again the phone with SP_Flash_Tool_v5.1628_Win and it worked but after starting the phone I realized that it had no IMEI at all.

Can someone, please, help?

I've managed to solve this with SN Writer

A problem when updating adroid 7, facebook and twiter applications do not work, then try to return android 6 per ota and when starting the phone does not recognize me imei someone can give me a solution please ????