Inspiron 15z 5523 - OS issue, fails to boot

My laptop is 4-5 years old and it's failed to boot since Tuesday after it cut out while in use on Monday night.

So far I've tried

Safe mode to remove recent software (NowTV media player)

System refresh

System restore

Running diagnostics/ePSA (no issues)

Initially I was getting different error codes (bad_pool_header, kernel_security_check_failure, ntfs_file_system and some others) seemingly at random so I decided to just do the system restore after all else failed.

Since then though it seems to be stuck on a preparing automatic repair start and crash when after displaying the logo. I've failed to find my recovery disc and after searching for my service tag on the support page there wasn't a stored image for my laptop available to download either.

Is there anything else I can try without needing to purchase a new version of Windows or having to locate a backup disc?

Thanks in advance for any assistance.