I just replaced my HDD with a 1TB Crucial MX500 SSD. It was easy to clone the drive and simple to install. My computer went from almost unusable to better than new, I highly recommend it.

I believe this guide would apply to most or all of the SP315-51-XXX laptops. I have a -79NT and the process and internals look the same.

That is a bummer, and something that concerns me as well. I’d like to replace the battery but it’s so common to get a failed battery or one that fails in a short period of time. Recently I’ve purchased two consecutive bad lithium drill batteries from ebay. Hope you get your computer figured out.