Hi & welcome,
First, How do you know it doesn't boot? Did you watch the HDD activity light & see if it goes throught the procees (Loads of flashing activity).
I would swap the graphics card for a known working one, then see if that boots & displays. If so, delete the hidden graphics card in device manager & then swap them back, to see what that has achieved.
If that achieves nothing (second card is good), I would then suggest the original card is fried.
If swapping the card also fails to? (Don't know why that would be).
Then I think you have toasted your motherboard but that seems un-believable & a little excessive for an update!
As a last thought, try swapping your power supply!