The new laptops have no screws for the VGA port.
From the specifications of your laptop, you have two ports for the monitor, VGA and HDMI.
This is the reason that Sony says you can use a single monitor with the screen of your laptop.
Maybe the new screen is not the one for your laptop, if you can't go into the BIOS, and you have nothing
on an external monitor, I fear that the problem is on the motherboard itself.