Hacking "My own Leaptop"

My daughter has had a "My Own Leaptop" (affiliate link) for some time, and the sound recently quit working on it, so I think it might be time to do a little hardware hacking ;) First, I'll check to see if I can fix the sound, but, if not, I'm looking at dropping in a Raspberry Pi. I'm not sure if the LCD will be usable at all, but it's pretty a pretty low-res black and white LCD without any backlight anyhow. This has been my plan all along, but I was going to wait for her to outgrow it first. One of the challenges will likely be the keyboard. It's not a standard keyboard, and there's not enough room to stuff a standard (even a mini) in the Leaptop unless I take a dremmel to it. I'm hoping to be able to wire the existing keyboard into a Teensy and make it appear as a standard hid device to the Pi. A bigger challenge is going to be finding a kid-friendly, keyboard-driven interface that will run with a limited keyboard. I'd also like to use the four-position switch that's underneath the screen, but I suspect it will be easy enough to wire this to some gpio pins and occasionally check the position of the switch. At any rate, if I'm unable to repair the sound, I'll be doing this sooner rather than later, and I'll post the progress as I go.