I recently upgraded my netbook (Lenovo S205) from 14.04 to 14.10. After the restart, it just restarts over and over. I see the boot menu where I can press F2 to get into BIOS and F12 to choose the start medium. Shortly after that it restarts. That's roughly one restart every five seconds or so. I tried starting from a live usb stick, but when I start from the usb stick it only says "secure boot not enabled" and then the screen stays black. In BIOS, there is no option that has anything to do with secure booting.
EDIT: By pressing some buttons (unfortunately I don't know which) I made it into boot-repair. However, after I let it repair everything and I restart, it's the same as before. Here is my log.