I have an accenta 6 alarm system, after a power cut the RKP is not working - the numbers are lit but the red power led is out. Searching various forums suggests that my battery probably needs replacing. I dont know the correct size both physical and amphours, so need to look inside the control unit. How do I stop the system alarming when I take off the cover of the control unit if I cannot enter a code ??

TC, June 2016

Open the lid
Alarm sounds
Put in your code, it stops
When done, close lid
Put in your code for the last time
Done

W, June 2016