Just refer to the solution below and analyze how each certain keypad keys being connected. This solution may also help in bypassing the keypad EMI filter IC.

1. Clean the keypad matrix including the keypad membrane.
2. Trace the connection line paths of a certain keys that doesnt work.
3. Check/replace the Keypads EMI filter IC or you can bypass it by applying a jumper wire on the open test point or spots as shown on the picture above. It will work too.

