To burn bootloader to Arduino MEGA 2560 using Arduino Uno as ISP, connect Uno & MEGA as shown:
PC is connected to Uno.
- Program Uno as ArduinoISP > Select board of Uno > Select programmer of AVRISP mkII > File > Examples > ArduinoISP > ArduinoISP > Upload
- Now we are going to program MEGA, the Uno act as Arduino as ISP. > Select board of MEGA > Select programmer of Arduino as ISP > Tools > Burn Bootloader