Why is the External Display not connecting to my device?

I have an old HP HDX16 (wow, its turning 16!) with multiple issues. Here are some:

• Computer screen seems to have completely broken due to water droplets forming on the inside of the screen over unused years. (Very hot and humid weather)
• Only working Power Supply beeps and only outputs 0.06volts, but after some time it may stop beeping and starts outputting 19.46volts.

The issue that I am specifically reaching out for is:

Why doesn't the computer display anything when connected to External Display?

You may think: Oh, its probably because the system doesnt boot.

But I believe that the computer is on, because the EJECT button does eject the dvd/blu-ray drive.

I have an UBUNTU 25 SSD that is known-good from being used on other devices.

Any Ideas?