Got the same problem in my MY02, press any button on keypad and it will start. On the odd occasion it does arm correctly, like 5% of the time. Arms correctly when the hijack mode is activated. Started couple months ago after flat battery.

Keen to see how he solves it.

When he sets off the alarm, is that just the soft warning alarm or the full on loud one (e.g. close boot when armed and soft warning alarm will go off, do it again and loud alarm will go off).