So.. I've screwed something up.
I have a Kindle 3, and I've had it jailbroken since I got it. It currently has the 3.1 jailbreak on it along with the screensavers hack. (I did check the software version, but promptly forgot it.

)
Today I decided to install a new font and followed the instructions on:
https://wiki.mobileread.com/wiki/Kind...nd_3.x_Kindles
Installation seemed to go fine and my kindle booted up with the home screen in the new font. However, when I tried to open a collection, I discovered that I've totally ****ed something up, because the device is stuck on the home screen. You can move the cursor up and down, but you can't actually open anything, including the settings page, which means I can't just run the uninstall.bin. (In hindsight, I think probably failing to update my jailbreak first is what's done it.)
The kindle turns off and on, I can access everything over USB, but I can't do anything on the device. I've rebooted a couple of times to no avail.
Do I have any options to fix this painlessly? I've heard warnings about resetting to factory default with a jailbreak so I haven't resorted to that option yet, but I'll resign myself to it if it'll fix my mess. Thank you in advance.