I set out to update my Raspberry Pi to take to the Hour of Code at the local robot school tonight, and after three hours of studious work, I've reduced it to a fragment of warm silicon.
Several months ago, it was a functional system with Mathematica, camera, Logitech cordless keyboard and mouse, capable of running from its command line or its desktop, and operating as advertised via ssh or from a Remote Development Control Panel on my MBP.
This morning, I booted, logged in and ran sudo apt-get update and sudo apt-get wolfram-engine. The wolfram command line was available and evidently functional from the terminal. I called up the desktop with start, but found the wireless mouse was inoperable. I consulted various web forums and followed the progressively invasive cures, but not worked. Finally, I rebooted in safe mode (held down the Shift key) and arrived at a screen from which I could reload the OS I had installed earlier - Debian.
After I rebooted, I again ran sudo apt-get update and sudo apt-get wolfram-engine, but this time I got E: Invalid operation wolfram-engine.
So I started with a running system, improved it by defeating key hardware functions, and finally optimized it by disabling the software. By now its too late to fix for tonight, but I need some hints on how to approach this other that buying a new one.