Greetings,
Welcome to the forum.
I am not a HP employee.
A 3:3 BIOS error code is a graphics card initialization problem. You reseated the graphics card.
Did you verify the power supply connection to the card is secure and fully connected?
No integrated graphics on your PC's motherboard. You may have to try a different graphics card to see if the system will POST.
You must disable Secure boot and enable Legacy support (Link) if you try a different graphics card. This creates a problem because you can't get to the BIOS with the existing graphics card and the PC may not POST with Secure boot enabled when you install a different graphics card.
Resetting CMOS to defaults won't help because the default setting for Secure boot is "enabled".
I can't think of any way to get around this roadblock. You may have to contact HP Support (Link).
Regards