After a failed flashing attempt(don’t attempt to tftp flash u-boot.kwb from within U-Boot!) I needed to use JTAG combined with the included JTAG adapter. To do this, make sure that the UART cable is unplugged, and the JTAG cable is plugged in(unplug/replug the USB adapter just to be safe). First grab the guruplug-installer package, then grab a known-good copy of U-Boot. $ cd Downloads/ $ tar zxvf Guruplug-installer.tar.gz $ cd guruplug-installer $ sudo .
At which point I decided I wanted to try to restore the original kernel, so that I would at least have a working system with which to test. Therein lied the rub. The files posted here are completely broken. Thankfully, a friend of mine also ordered a GuruPlug. So I grabbed his images. Here’s how to ACTUALLY restore your GuruPlug if you flash a bad kernel to it. Download the extracted uImage.