veritas R8 - gone off, tamper light on, code not accepted......HELP!!!!?

Early this morning my veritas r8plus system went off after a power fault. Entered code, would not stop. Tried everything but could not get the alarm to stop - did not work when entered code, reset button etc etc.

Alarm has stopped but keypad now has unset and tamper lights on, one zone flashing and another solid colour. When I enter my code it mkes a flat beep sound when you press each button. Just realised battery was fitted in 2003 so needs replacing.

How do I get my alarm working again.....HELP!!!!!