Answer to "No ring sound after changing charge port."May be what I am saying is write answer or not but I too had the same problem but the only solution is put the charging completely until it completes 100%. I think the mobile while charging gets compatible with power supply and when we replace the socket it take some time to compatible with power,for example when the power supply is gone in home all components get closed or stop working ,suddenly when it comes back one by one started working (components),the low voltage bulb turns on first whether the high voltage on at last.In the same way our mobile components work similarly.
Answer to "Lenovo k5 note mobile network goes on and off frequently"Hello , The basic reason for this is you should not on your mobile data @24H and also while your charging your mobile you must set in an aeroplane mode or switch off it, because the usage of mobile and also the heating comes from it is consider first problem domain. The signal is not constant and the place you are living is also not constant, While your are not using any app frequently better to turn off notifications for that.