I have a self assembled Arduino Mega2560 board with Mega16U2. An example sketch compiles well but the upload bar never go to the finish.
There is Com port for Arduino and everything seems to be well on the PC. I used these firmwares for the chips: For the 16U2 C:\Program Files\arduino-1.0.1\hardware\arduino\firmwares\Arduino-COMBINED-dfu-usbserial-atmega16u2-MegaADK-Rev3.hex
And for the ATMega2560 C:\Program Files\arduino-1.0.1\hardware\arduino\bootloaders\stk500v2\stk500boot_v2_mega2560.hex
I used AVRstudio with AVRISP for burning firmware. How I can get a hex-file from Arduino IDE. I could burn it with AVRSTUDIO.
Unfortunately there are no LEDS on the board. But power is ok 5volts.