Take it back out and see how it goes? If it works, go into the BIOS and make sure it is set to allow 'auto' or 'detect' graphics output method. It might still use the onboard output. You could try ...

Is your PC not booting after updating BIOS? Some users have reported that they can’t boot their computers right after installing a BIOS update. While the issue is likely to occur due to a failed BIOS ...