This just started happening, or it never worked (is new)?
Relichost person seems on track.
Are the other servers on the same UPS having the problem? Is it under warranty?
Besides checking for voltage and heat problems, I'd try taking it apart and putting it back together snug. While doing so, you may find a problem or put it together right the second time. Finally, if that doesn't work, swap out components until it's fixed.
However, while you have an OS on it, have you looked in the logs after booting it back up?
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