New house no alarm code

Moved into a new house, previous owners didn't use alarm and don't know the code. They owned house from new.

The issue I now have is when there is a power cut or I turn power off, the house alarm goes off due to low battery in the alarm box. Due to not having the code i am unable to open the alarm box to change battery without setting off the tamper alarm.

What is my best course of action? Ideally I want the alarm to be fully functional and have a code so that it can be utilised. 

It flashes "runner series" on LCD. Unable to attach a pic, perhaps due to being a new member. 

Thanks in advance for any help 

Find a copy of the makers installation manual. Some alarms can be reset to factory settings.  Initially I think you are likely to have to remove the batteries with it sounding, but it only takes a few moments..  There is probably a small battery in the external bell box as well as the one in the panel.

I am also assuming they left no manuals? is this a wired or wireless system? It may be possible to reset/default it back to factory settings, but then you need the programming guide to reconfigure it. Also, you don't know if it had any other reliability/false alarm issues, (sometimes the case where people stop using a system?).  If it is a wired system, in these situations it can be less hassle just replacing the panel so you are starting afresh with a know-working system, (sensors/wiring & external sounder probably re-usable).  The first thing you need to establish is can you obtain copies of the user & programming guide for your system.

Doc H.

Try the year that house was built as the code, it is common to use that as initial code which is then changed by the new occupants. 

I've updated your account so you can post pictures, if you'd like.