Problems with an Ademco Vista-15... System won't arm, and it keeps counting?

[iratable@xxxxxxxxx]

Hoping someone might have run into this problem before. I've got a 5-
year old Ademco Vista-15 which refuses to arm.

The control pad -- a fixed-word display -- has a "check" status
indicator on, and the alphanumeric section where I would expect to see
zone data is counting from 49 to 63, then starting over again. (And
over and over and over.)

When tripping the sensors (total of 2 motion + 3 door) the control pad
is correctly identifying the zones that are being triggered. Inputing
the master code to turn the system off, place it in test mode, adjust
other codes, or anything else for that matter seems to have no effect.

Anybody run into something like this before? Could it be a simple
matter of replacing a battery or something? (I couldn't find any
descriptions via Google that matched my problem, so I'm not so sure.)

Many thanks in advance for the help...