Thanks, it's definitely not a warning beep. I've read through the manual and the beeps are too random for it to be a warning, and there's nothing in the fault logs. The warning light doesn't even come on. The keypad becomes unresponsive when it happens which supports what I've observed about it being the up button triggering as I wouldn't expect you to be able to press two keys at once.
We inherited this alarm unit when we moved house so don't know if liquid or smoke played a part, although it's position on the wall would suggest not. It doesn't even seem to be that the key is sticky as it doesn't occur after the key has been pressed, it's completely random and intermittent. We went for weeks without it happening and at the moment it's happening at least once a day (usually in the middle of the night ) and our only option is to completely switch the unit off. It seems like it might be some sort of fault with the button electronics or the membrane. I might try giving it a clean and see if that helps before we have to start looking at replacing it.
We inherited this alarm unit when we moved house so don't know if liquid or smoke played a part, although it's position on the wall would suggest not. It doesn't even seem to be that the key is sticky as it doesn't occur after the key has been pressed, it's completely random and intermittent. We went for weeks without it happening and at the moment it's happening at least once a day (usually in the middle of the night ) and our only option is to completely switch the unit off. It seems like it might be some sort of fault with the button electronics or the membrane. I might try giving it a clean and see if that helps before we have to start looking at replacing it.