Just an update
After reseating all connections etc that I could see and still not getting the laptop to boot, I put it on one side until I got a chance to drop it into a repair shop for an estimate.
Tonight I thought ok I will just try it before taking it in tomorrow, switched it on and it came up with a screen “windows failed to start “ do you want to run repair. Hit yes and left it to it, result is its now up and running.
It looks like it is a motherboard problem somewhere, either a bad connection or a crack. Otherwise why would it not even try to boot then suddenly burst into life, I wonder how long it will run for before failing again?
I have tried shutting it down a few times plus loaded it with a DVD conversion while surfing and it kept going. Strange things these computer gremlins
Max