Ubuntu :: Computer Dead After Failed Apt-get

I was running some python code, and I wanted to RAR some result data. I did a sudo apt-get install rar, but the installation got stuck so I killed it with ctrl-C. Since that might result in a broken package, I tried opening synaptic with sudo synaptic but it wouldn't start because apparently apt-get is still running in the background.

I tried to kill the process with kill $(grep apt-get) but it didn't work. Then I tried turning off my computer but it got stuck at a loading screen saying something about an incomplete install. Finally I just pressed the reset button, but instead of restarting normally, it beeped 2-3 times and nothing would show up on the screen. I repeatedly turned it off, wait a while, then turn it on, but nothing works. I tried unplugging everything (mouse, keyboard, internet, etc) except the monitor, but that didn't help. I tried hooking it up to another working monitor, but still got no improvement. The cause seems to be software-related but it's behaving like a hardware problem. By the way, the computer is dual-booted with Windows XP and Ubuntu but Windows wouldn't start either. Nothing at all shows up on the screen.