It's been a while since I last battered one back to life, the the CB's on bev.makers were, and probably still are, "tempermental" and prone to tripping with minimal overload. I would always look at these first therefore.
On the other hand, human factors can play a part.
Called to the rear galley for an "emergency ! " just prior to push back. Arrive to encounter "madam" who duly launches into a "what sort of customer service is this !..was I the engineer responsible !..how dare I provide this level of service for customers"...etc, etc. and all within earshot of the pax.
One waited and duly opined that, whilst one was merely a "thick engineer" said with suitable sarcastic inflection, one wondered if "madam" had studied English and Physics at school by any remote chance ?..if so, "madam" would have noted, as one kindly demonstrated, that if she moved the water supply knob from, erm, "Closed" to "Open, then, oh look, water doth flow!.
Less than muffled laughter from the adjacent pax and a few smiles as I left the galley.