Here's The solution for Nokia E5 keypad malfunction. This is very useful in troubleshooting certain keys that won't work or not responding due to wet damaged. This solution completely shows each corresponding keys line paths and connection including the keypad filter IC.
Nokia E5 keypad failure solution - keypad filter IC jumper ways
There are two EMI filter chip is being used in the circuit and it is located near the battery terminal. This keypad filter can't be found from old Nokia models.