Scantronics 9651 - and 9330 keypad?

Hello,

My alarm started to beep intermittently and key pad display saying MISSING BATTERY. I didn't panic as I had dealt with this previously and had only put a new battery in 7 months ago (although was concerned the battery had only lasted 7 months when the last one lasted 8 years!)

Left it a few days and done an engineer reset - sorted.

Two weeks later the same beep beep beep but this time it will not let me input any numbers at all.

Took lid off to replace battery and whilst the key pad displayed LID TAMPER no siren sounded. the two message alternated until the lid the Battery was changed an lid replaced then display went back to MISSING BATTERY however still will not accept any number I put in.

So any ideas and advice or is it royally caput??