EQUIPMENT STOPS AT STEP CHECK. INDICATING HARDWARE ERROR [31-6]

COULD ANYONE HELP? I AM HAVING AN ISSUE WITH MY DR 3900 SPECTROPHOTOMETER SHOWING HARDWARE ERROR [31-6]. INITIALLY IT RESETS AFTER REBOOTING, BUT LATER NO RESPONSE AGAIN. PLEASE AN URGENT RESPONSE AS TO WHAT TO DO TO CLEAR THIS ERROR WILL BE APPRECIATED.