How do I know my laptop just experienced a power surge?

Just got a brand new sony vaio cw series and it crashed yesterday. I figured something must be wrong with the product and that I need to take it to best buy and exchange it but my aunt told me that it could have been a power surge, since I live in a college dorm thats pretty old. However I have 3 other friends who live in this dorm and they don't have power strips with surge protection for their laptops and have never experienced their computers failing on them so I doubt it. But just in case, what are the signs that my laptop experienced a power surge? My laptop's screen turned gray and made this loud buzzing noise for 3 minutes, which was when I turned the computer off since it wasn't stopping. Now it's working again but I still don't know what happened. So again what are the signs that a laptop experience a power surge? Like heat etc.....