hello
I have other hardware which is based on the exact same Ralink RT3052x SOC and when I use the reset button on start up uboot will listen for http connections for about 10 seconds allowing me to update the firmware. Is the same thing possible with Carambola? If that is possible: what is the default IP of Carambola uboot boot loader?? I tried 192.168.1.1 but it is not working.
I am asking because I made a mistake upgrading with the wrong firmware using sysupgrade and I can't connect to the board anymore. I am sure that uboot is alive although I didn't check with serial connection yet; but it should be working since I didn't try to modify the boot loader in anyway..!

I also need to download the image that was on Carambola when it was shipped. it contained a very nice web interface to configure the board. I really appreciate it your help.

Thanks for your help.

I doubt uboot does that on Carambla. However, updating the Firmware with uboot via TFTP shows that uboot has a default client IP address of 10.10.10.123 and looks for a new image at 10.10.10.3 named test.bin.

I'd just connect a USB to serial cable to your PC and use your favorite serial Terminal software to connect with uboot. It's really easy and less hassle than the method you described.