Here's the Nokis 2690 Solution for charger not supported problem. This problem shows if the device battery charger is being plug-in and it shows "charger not supported" on the display.
To fix this problem, you may first try to replace the phones battery and use another working charger.
If the problem continue occurred, refer to the solution below and try to replace the highlighted component.
Locate the component's showed on the solution above and then try to replace it, it is the battery temperature (BTEMP) 47K resistor. When the damaged it will result to the Nokia 2690 charger not supported problem.