Hello,
I have trouble trying to burn the bootloader to a Mega 2560. I was playing around with icsp header and an old programmer called GTP-USB Plus (Page with what AVR does this programmer supports), which supossedly supports ATMEGA2560, when I tried to clear the MEGA and then burn the bootloader. To my surprise it cleared and burnt the bootloader too fast. When I tried to put again in Arduino IDE, it detects the ATMEGA16U2 usb serial port but not the mega 2560.
So I tried to make one of my Nanos to be an ArduinoISP programmer and burn the bootloader using the Arduino IDE or the gui for AVRDUDE, AVRDUDESS, but I always get error signature is 0xff... or 0x00...
I have connected the same way as here, but to the mega icsp pin.
Thanks in advance.