Yun UBoot Prompt Not Showing I have a Geeetech Iduino Yun Shield. I accidentally flashed the wrong firmware image (not the sysupgrade) to the board. I then tried using the Yun UBoot Reflash method. However, when I open the console monitor from the IDE and restart/reboot the board, I do not get the UBoot prompt. I have attempted to run it at least ten times without receiving any console/serial output.

EDIT: The shield is running on a Leonardo base board.

Is there anything I can do to load the correct firmware onto the board and get it operational or is the board truly bricked? If so, is it possible to obtain a new Atheros AR9331 board to replace the existing one or should I buy a new Yun?

Update: I have tried to get the shield to do an FTP boot, as detailed here by Majenko. I get to the stage where I get the dr_boot&gt; prompt. However, when I type in tftpboot 0x81000000 dragino2-yun-common-v2.0.6-kernel.bin, I get no feedback; it just sits there indefinitely (unless I interupt the process). I can't figure out what I'm doing wrong.
The shield is very different to the real Yun when it comes to serial communication.

Typically the Atheros's UART is mapped to pins 0/1 of the shield for communication with the board it is plugged in to. Those pins are also the pins you use to communicate with the PC, so the normal YunSerialTerminal sketch can't be used. 

Instead you will have to lift those pins out of the socket they go into (depending on the shield you may just be able to bend them slightly) and then manually connect them (along with ground) to an external USB to UART adaptor (e.g., FT232) to use for the communication.  Nothing needs to be installed into the Arduino board since that is now just being used as a power supply.

See this answer for which pins to use to run the shield stand-alone.