So my girlfriend's "oldish" MacBook Pro (Model #: A1286?) won't boot. Upon pressing the power button the fan starts up and a short mechanical noise is heard that sounds like the DVD drive's loading mechanism. Then the screen comes up mostly whit with the pictured pattern.
If I leave it running the screen will periodically turn black shortly, the mechanical noise will be heard again and then the weird patterned white screen comes back. The pattern is not always exactly the same, but always similar to the one pictured.
All troubleshooting tips I was able to find assume that the machine boots to at least the apple logo, which this definitely does not.
I would appreciate any input as to what might be causing this and / or how to fix it.
EDIT: Almost everything I have tried so far has included holding down some sort of key combination on startup. But all those tips (like the ones from Monomeeth's answer) usually reference the "grey startup screen" or the "screen with the apple logo". My MBP does not display anything but the weird pattern above, so I can't run the hardware test, boot to safe mode or reinstall the OS.
But since I've tried Resetting the PRAM/NVRAM the MBP sounds the "startup chime" on every reboot which it hasn't done before as far as I can remember.
Sadly I'm not 100% sure what year the MBP is, but it should be 2010 (or maybe 2009)
As suggested by Allan I tried hooking it up to an external monitor, but the external monitor stayed black while the behavior of the MBP did not change at all.