HI, These UPS units have a simple count down clock on their logic boards. It is a case that even replacing the fans (or batteries if it is a 'battery service message') does not cancel the alarm. Chloride (now Emmerson) have the ability to cancel the alarm with software, of course this is at a charge !!. One way to cancel the alarm is to drain the battery retaining the clock information. This resets all of the alarm clocks int he UPS. You have to switch off the UPS and disconnect the supply input totally, then disconnect or remove the main UPS batteries. The little battery on the logic board will then slowly discharge. You need the UPS off for at least 4-6 hours. By then the logic battery will have fully discharged. When you start the UPS up again the countdown clocks will reset. They will come back on again in either 3 or 5 years time. Same with Masterguard units. Good luck