The SSD went and I kept getting a flashing file icon with a question mark in it everytime I tried to boot it up. Diagnosed with Apple that it was a faulty SSD, but they quoted me £1000 to fix.
I had the SSD replaced with an independent shop. The MacBook now turns on and prompts you install OS through disk utility. Once it's downloaded, it resets like you'd expect but takes you straight back to disk utility to install OS. Essentially, it does all the process, but doesn't install any OS.
I've tried the original OS and the one the SSD was using before installed (bought from eBay, but the shop is adamant it's not broken because it can read and boots up.)
I would really appreciate any help, advice, or relevant information otherwise.
Let me know if you'd like any further clarification of the issue.