Here's the solution for Nokia 6124 classic with keypad not working problem. This solution shows the connection of the keypad matrix of the phone.
If some or all of the keys stop working or responding, you may first try to check the keypad flex matrix for possible damaged, dirt or oxidation build -ups. Ensure that it is absolutely cleaned. Replace the keypad flex matrix if severely damaged.
If the keypad flex seems okay but some of the keys either like, 1 ,2 ,3 ,4 ,5 ,6 ,7 ,8 ,9 ,0, #, *, left, call, soft left, up, down, right, soft right or select that does not respond, refer to the solution below and locate the keypad filter IC and do have a check and or replacement procedure.
If some or all of the keys stop working or responding, you may first try to check the keypad flex matrix for possible damaged, dirt or oxidation build -ups. Ensure that it is absolutely cleaned. Replace the keypad flex matrix if severely damaged.
If the keypad flex seems okay but some of the keys either like, 1 ,2 ,3 ,4 ,5 ,6 ,7 ,8 ,9 ,0, #, *, left, call, soft left, up, down, right, soft right or select that does not respond, refer to the solution below and locate the keypad filter IC and do have a check and or replacement procedure.
Nokia 6124c Keypad Filter IC Connection Tracks
The keypad filter IC is mounted or located near the LCD pin connector. You may then try to replace it with a new replacement spare. You can also track down its connection for possible cut-off or open circuit.