There are many ways to try and restart the computer, however the first thing to do is to know whether Nick has installed any recent hardware or software that might have a virus and caused the shutdown. Or there was an installed hardware that did not match the specs and it damaged the components of the computer.
1) As you would try to restart the computer, go into safe mode and try to disable these programs. While in safe mode - go to the run command and type msconfig - - in the startup tab - click on disable all and reboot.
2) Try tapping the F8 key as its booting up then select "Load last known good Configuration" System will reboot and hopefully boot up
3) Set it aside for sometime and then press the on/off button of the computer to let it reboot.
If any of these do not work, it would be best to ask for help in the tech support.