Try these things:
Go to Settings, then Locatin services, and uncheck both options.
Then go to Profiles, Edit, and go to profile you are using and select "Manage Content"
Go down to Apps. Open that up and make sure your nook apps that you are looking for are checked (evernote,pandora, etc.) While you are at it, uncheck any new apps you dont want.
When you open up your Evernote account, go to settings and change the sync option to what you need.(Auto syncing in background uses more battery even when app isnt open.)
Turn the unit completely off. Turn it back on. See if better. Hope that helps.