Try a new MagSafe power adapter.
Assuming that you have MBP 15 inch, 85W power adapter is the one to be used.
If it is MBP 13 inch, 65W power adapter will do.
You have performed all the standard troubleshooting steps one can suggest.
Try unplugging the power adapter from the wall and plugging it back.
I do not know what effect deleting the PowerManagement.plist will have.
HD > Library > Preferences > System Configuration folder >
If you try this Energy Saver settings in System Preference have to be reset.
May be nearby Apple Store can help.