On upgrading from 12.04 to 12.10, the system wouldn't reboot, it just hung. I decided on a clean install and rebooted from a USB stick with the 12.10 ISO image. On installing, it detected that 12.10 was already present so I chose the "Reinstall" option.
It seemed to hang on reinstalling (spent about an hour doing seemingly nothing, so I turned off and rebooted, having decided to go for a clean install. However, the netbook no longer boots from a USB stick. When I hit ESC or F2 I get the option, but it either skips straight to the hard drive (and broken system) or dumps me in the BIOS. I've tried changing the boot order, but it still skips over the USB.
I've tried other live USBs and the same thing happens. I've also remade the live USB, but the issue continues. Is there any way to rescue this netbook?
Edit - Booting from the hard drive takes me to a BusyBox shell. Is there anything I can do from there?