MI4c. after installation of 6.3.17 connection with MI Band has a lot of problems; connection is ok only after 3 or 4 attempts, often i need to swich off bluetoot and then on; vibration is ok for calls and sms but is absolutely no working app addition (i.g. whatsapp); configuration is ok but no vibration at all. The same happens with the app Mi Band Notifier. Due to the fact that with 6.3.10 all was working perfectly, someone could help me? It's possible the problem will be solved in next issue? There's a way to roll back to 6.3.10, i tried but no sim detected and other notice of malfunction. So i returned to 6.3.17, and, for the moment i keep my Mi Band problem. So, conclusion, someone could tell me how reinstall 6.3.10? Safely? Thanks. Of course this expecially for ingrbrzy, i mean.