It sounds like the heatsink has come off its mounting. Its turning off because of the high temperature the CPU is running at due to the heatsink not being properly attached. While I have no experience with that particular laptop, I would suggest purchasing some Arctic Silver 5 or some other thermal paste. Take it apart and remount the heatsink. Although its also possible the mounting mechanism could be broken so you might need a new one. Also do not forget to wipe off the old thermal pad/paste with some high purity rubbing alcohol. Check google, I'm sure there are many guides on how to change CPU heatsinks.