I was doing the same thing and finally found a work around. To unlock phone you can turn on one of two things under Motions and Gestures. Open Settings> Advanced Feautures> Motions & Gestures and make sure either Double Tap to turn on screen or Lift to wake. This allows you to avoid having to plug-in and unplug to wake it.
If you need to take a screenshot, make sure you have the Accessibility Button active, include the Assistant Menu a Shortcut and you'll have a Screenshot Option, Power Option and LockScreen Option. Hope this helps! I know it was frustrating for me prior to figuring these out lol! There may be more workarounds but I stopped when I found these!!
