602 PMC alarm : SDCC (Serial transmission error) Fanuc 0T

In case of OT alarm nos 510 etc.When m/c put on with P & CAN pressed then alarm 602. to counter this alarm, i did following:

a) checked for moisture, open cable M3 - KM1(from Keyboard to CNC), clean connectors M3 & KM1 with petrol

b) ensured none of the keys on keypad, remained stuck up and not getting released.

c) cleaned key pad carefully to avoid problem with Keypad matrix.

ADDITIONALLY, CAN U PLEASE ADVICE FURTHER?

Thanks