I tried searching for a solution to this issue within the forums but wound up empty handed.
My problem is this: according to the Arduino IDE, I have successfully uploaded the Marlin firmware. This is confirmed on the LCD screen while the boards are plugged into the computer. However, the interface is only accessible from the computer from which I uploaded the Arduino sketch. Said another way, when unplugged from the computer, and powered by the power supply, the Marlin firmware is not accessible that is, I only have a blank LCD screen when the Ramps/Mega board is unplugged from the uploading computer.
See pics for reference. Any help would be much appreciated.