I fixed mine last week. Pulled off the cover and battery, pulled the power button off, carefully, it's attached with self-adhesive. Opened the black plastic around the button - in the right side. Took the small metal out, cleaned it in isopropyl and did the same with the internals of the plastic wrapping. Put the metal back, and put the plastic wrapping back on the self-adhesive.
(and actually put a small folded piece of paper under the plastic wrapping, to lift the power electronic closer to the mechanics in the cover)
Sent from my Desire X using XDA Free mobile app