A few weeks ago my friends and I hiked up Mt. Marcy, in New York's Adirondack region, so I brought along a 702 to gather any interesting ambience we'd encounter. The peak's only 5,343 ft, but temperatures were down at 10-15 F. Around three-quarters of the way up, the 702 developed an odd, loud, stuttering buzz on both channels; it seemed to be triggered by pressing the record button, but was just as likely to start without provocation. By the time we reached the top, the 702 refused to boot up. Only after we had descended halfway did the 702 finally turn on again.
Could it be the battery? I'm not sure because the 702's buttons, etc., would light up as long as I held down the power button, but the device just wouldn't boot up. Perhaps it was condensation then? Odd.