How can I repair my Melcom ST6500?

Melcom ST 6500. While replacing PIR sensors, I accidentally shorted two wires setting off alarm. Had to turn of mains and disconnect battery briefly to stop alarm. Sensors are responding to movement, keypad touches make sound, but control panel LEDs will not light and green/red leds on bell box not working. Fuses in main box are intact.
Any suggestions please.