I have 3 x MGE Pulsar M 3000 2700w UPS units within my server room which have run perfectly up until now.

On Saturday morning I noticed that one of these UPS units was no longer outputting power, the lcd displayed a message saying "load not powered" and told me to press the power button to start output. Needless to say that the servers, switches and routers is was supporting were all turned off.

I tried pressing and even holding the power button, but the unit refused to start back up again. Only power cycling the unit got it back up again.

I have checked the logs on the UPS, although they were useless. Nothing out of the ordinary, and no email notifications had been sent. The output level sits on about 51% and all battery checks are OK.

It is now three days on and the UPS is still up and running (although I am scheduling an outage to get it out of there ASAP). Does anyone have any idea what could have gone wrong here? Is there anything else that I can check that could help?