Accenta keypad power light off and it will not accept a code. ?

Just moved house and have an Accenta Mini panel with 3 downstairs PIRs and one keypad. PIRs flash ok and main panel light is on.
Keypad background light is on but the mains/day indicators are not lit and it does nothing when I input the code the seller left.
How do I fix please and will it trigger the external siren when I try the fix? Many thanks, David