SO.... this is more a knowledge article, and I figured as it took me several hours of testing, trawling, headbutting walls I would post this to help everyone in the future.
Scenario:
I had a Vostro laptop 2017 (15 3468) that wouldn't power on, from experience I did the normal thing of drop out battery, discharge power etc to release any static, and Voila Laptop powered up. Check logs revealed a chipset error/driver problem " WHEA-Logger Event ID: 17 - A corrected hardware error has occurred ". So I did the Dell detect for drivers/updates and it found the relevant chipset drivers. Including a BIOS update. What I didn't know was this device was 'Bit-lockered'. So the BIOS update royally ruined this machine. (Not to self: ALWAYS read the instruction details on the driver page), It proceeded to then show No dell splash screen, a little back...