Hey,
I had similar issue with my bluebud X
Volume button work perfeclty, but power button work half the time, and stick when working (button stay down witch result in power off after 2 sec)
Source of problem:
After dissasembly, i realise the metal cup making contact for the power button had moved
Short answer:
replaced the metal cup to it's original place
Long answer:
remove the back cover of the button-mic assembly (8 small clib, 4 per side)
remove the red holder (6 clip, 4 per side)
be extra carfull with the small wire ( i recomande taping the earphone on a table will working to eleminate any strain on those wire)
remove the board (mine was slightly glued in place)
remove the tape holding the metal cup
place new tape on metal cup
Place tape + metal cup dead center on the + sign on the board (do not block the mic hole)
power on earphone to test
reassemble carefully (don't pinch small wire)
Picture while disasembled:
https://s13.postimg.org/51bmdx1yf/jaybird.jpg