Hi Jonny,
At this point we need to make sure this is not a software issue with your MacBook Pro. Depending on the version of the operating system installed on it, one of two ways -
If using OS X 10.6 or later, boot from the Recovery Partition -
OS X: About OS X Recovery
http://support.apple.com/kb/HT4718
In particular,
To start your computer from Recovery, restart your Mac and hold down the Command key and the R key (Command-R). Press and hold these keys until the Apple logo appears.
If using Mac OS X 10.5.8 or earlier you will need to try to boot from the install disk that came with the computer.
Startup key combinations for Intel-based Macs
http://support.apple.com/kb/HT1533
Press C during startup | Start up from a bootable CD, DVD, or USB thumb drive (such as OS X install media). |
If these fail - that is your symptoms persist even when booting to either the Recovery Partition or install disk, you will want to have your MacBook Pro serviced. Use the contact methods for your location described in this page -
Contact Apple for support and service
http://support.apple.com/kb/HE57
Thanks for using Apple Support Communities.
Best,
Brett L