RKP will not function?

my son entered his house the entry tone started as usual but on entering his code the the alarm timed out and a full alarm commenced at this point i etered and powered down the veritas R8 panel on checking the system the numbers 3,6 and 9 buttons were dead and of course these are contained within my sons code.I have replaced the keypad powered up wiated for the entry tone and tried the key in the user code to find that no all buttons are dead any ideas9 RETIRED ELECTRICIAN/LECTURER no tampers showing checked resistances of all circuits ok