HP 35s won't turn on

[Mackpeirson]

I had this calculator for about a year. Recently it refused to turn on. One day it was fine, the next it seemed dead. New batteries don't make any difference. Is there a trick when this happens, or is this device repairable? One good thing, though; this prompted me to find a 41CV on eBay, which is in good shape. I have already programmed a feet and inches converter/calculator, since my work on industrial fired heaters involves doing take-offs from a lot of old equipment.