Bootloader Arduino Mega 2560


I have a project in which I need to change the Arduino software without the need to be connected by USB.

From what I've been looking at may have 2 options, you flash the Arduino from SD, or read the Arduino software directly from the SD.

For any of the 2 options would need to create a bootloader (For the first option 2boot there, but I can not get it to work). Can anyone help me?

We could talk about paid work.

Regards and thanks!

Check out this approach from SD card: