Even if you removed mains power and disconnected the battery and grew a beard, she wouldn't revert to factory settings.
As gts has said he`s got ya,
this happeneds all the time,when we install or take over a system we change all defaults,and set tampers on engineering,
that way you either have to contact us, or pay for someone else to restore/reprogramme.
you are lucky with your panel as it will factory restore if you follow the manual to the letter,
as you aren't confident in the procedure, you have no choice in paying the man,or finding another engineer.
I can tell you that me personally, I will give the engineering code to the owner if he is present,and requests it.
no name, April 2012