After pulling the new cooler off, re-seating the ram and cpu 4 times, trying 1 and 2 sticks of ram alternating (which was a pain with the blackridge cooler as had to remove it to change ram options) and countless re-boots, I have managed to get it to prompt.
Now the scary thing is I need to pull the cooler off again, re-paste (as the only paste have is Kryonaut and didnt want to waste it all) and also switch out the stock black ridge fan for a noctua.
Guessing when levering the bracket off the back of the mobo I flexed it too far the CPU un-seated itself.
Phew.
Good news is my pc is now sitting on a motherboard box on my desk, so should be a quicker transfer into the T1 lol