This solution may possibly help fix Nokia 6720c charger not supported problem.
When the battery charger is being plug-in to the device and it shows charger not supported you may refer to this solution below for it shows the certain component that may possibly caused the problem.
Nokia 6720c Charger Not Supported Solution
You may just try to replace the BTEMP (battery temperature) resistor shown on the solution above, this resistor has a resistance value of 47 kilo-ohms
