Hello,
I´m trying to update the sketch of Arduino nano from the EEPROM. I have two Arduino nanos, one is the programmer and the other is the application. The programmer reads the EEPROM and sends the data of the sketch to the other Arduino via hardware Serial but this doesn't work.
The Serial baud rate I put 57600 and to program I reset the Arduino, i write all the sketch without any extra information and y reboot.
What am I doing bad? How does the bootloader work when we update by the Serial? 
Thanks!! 