headviking

we just moved into a new house with a DSC 1616 power series alarm installed. Not sure if it was monitored or not. I do have the master code but not the installer code. The key pad was a bit banged up so I opted for the PK5500 instead of replacing the PK5501. Now I have an error triangle with dashes on screen. How can I get it to work with out error screen and showing status on screen. I believe it has been lock out. What can I do? Please help John