Excellent! Rebooting now would make things quite hard to recover indeed. Looks like you've attempted to upgrade with the SDK repo enabled, causing conflicts with busybox. I'm not familiar enough with Debian packaging to be sure what you should do from here, but I think none of that would work anymore. As I understand it, you are currently stuck with no tar, and probably no shell, so installing packages may not work... First order of business, then, would be to get busybox back on, and all relevant links reinstated. You've got a busybox in /mnt/initfs, but it's linked against a different libc, so you can't just drop it in here... All I'm thinking is to rip busybox out of another system (on an SD, if you have one).