Sony Laptop

I just had a sony Vaios restored buy Best Buy.
The warranty just expired. I have T.V on it ect.
When I got the laptop back, I am able to run the laptop on a solid surface, but when I roam with it on my lap I get a blue screen. Is there a chance that when they rebuilt the laptop that they didn’t seat the hard drive fully?
Can I access the hard drive from the bottom of this system????

Thanks
MWhite