Turned my ignition, nothing then a whirring noise from the back - what happened?

[notworthy]

Hey all,

I need some technical help please. I turned the key on my boxster (2003 2.7) for a normal start and it didn't start or tick over however a whirring noise from the back went into action and stayed on for about 30 seconds (felt like a minute). During that whirring noise time I had turned off the ignition and had the key pulled out.

Has anyone experienced this before and/or have an idea of what just happened.

The noise was still going even with the key out of the ignition!

I waited until the noise stopped, turned the ignition again and it started really abruptly (almost perfectly) and no issue at all. Really strange.

Thanks, I look forward to your responses.