MacBook has died blank screen, charging light is green but nothing from power button?

Try an SMC Reset.

Try unplugging the charger from the electrical outlet for a minute to reset the charger's internal circuitry.

There is a chance the battery is bad or completely discharged which can prevent the Mac from powering on or even charging. Sometimes disconnecting the battery and powering on the laptop using just the charger will prove this diagnosis. If the laptop powers on you can reconnect the battery while the laptop is still powered on which can sometimes get the battery to start charging again, but make sure to let the battery charge at least 10% before powering off or disconnecting the charger (plus you must be very careful not to let any metallic/conductive item or surface make contact with the internal electronics.

Otherwise you likely have a hardware issue most likely with the Logic Board, but possibly the DC-In Board or Keyboard/Trackpad.

FYI, when posting on the forums for assistance it helps to provide the exact model of your Mac since each model may have some unique issues. You can get the exact model of the Mac by entering the serial number on this link:

https://checkcoverage.apple.com/

Edit: Here is a link to the SMC Reset procedure:

http://support.apple.com/kb/HT201295