Got an Arduino board, great programming and fast learning curve... but no way to have it going as standalone. Each time the power is cut off, when re-powered all is dead but the green "Power" led; both with usb or ext power supply, resetting or not resetting. I've read for clear that one of the main features is to keep last uploaded code, and when re-powered and resetted, after 5 secs. the code should load and start to go. Where I'm wrong?
"Why doesn't my sketch start when I'm powering the board with an external power supply?
Because the RX pin is unconnected, the bootloader on the board may be seeing garbage data coming in, meaning that it never times out and starts your sketch. Try tying the RX pin to ground with a 10K resistor (or connecting it to the TX pin)."