How to burn Arduino bootloader to Pro Micro by Nano.
Step 1: Burning Bootloader
So, you need to burn bootloader to Arduino Pro Micro. You have good Arduino Nano.
1. Prepare Master:
Connect Arduino Nano to PC.
Open Arduino IDE 1.8.5
Arduino IDE: Tools-> Select Board -> Arduino Nano
Tools->Processor-> Atmega328p (old bootloader) # I buy board made in China
Open File->Examples->11.Arduino ISP
Arduino IDE: Tools -> Select Board -> Arduino Micro
Tools -> Programmetor -> Arduino as ISP
Click: Tools -> Burn bootloader
Wait about 1 minute.
2 LEDs on Arduino Pro Micro will fired when finished.