Arduino exit status problem

Development Tools Uploading
7
  1. Did upload work in the past?
  2. Anything connected to pins 0 and 1? This will interfere with the upload so disconnect and try again.
  3. Anything else connected? Disconnect it and try again. If yes, what else is connected?
  4. Is COM3 indeed the Mega? Does the port disappear from the IDE's ports menu when you disconnect the board?
  5. If your board does not use the CH340 serial-to-usb converter but e.g. 16U2, what is the result of the loopback test?
  6. If you tap the reset button on the board, does the L-LED flash a couple of times?

I've moved your topic to the section of the forum that is dedicated to this type of problems.