Why, after reconnecting power, is our key pad not accepting the code?

After reconnecting the consumer unit does the Texecom Veritas alarm will not work? We have reconnected the internal battery then turned mains power back on at consumer unit. Put the cover on and screwed the tamper screws back. Result= the alarm continuously beeps. I enter our code it does nothing. I've tried the 1234 or 4321 nothing. The whole alarm system then kicks in and both the internal and external bells ring. Thanks for any help. Sharon