No video output from VGA card?

Try different VGA cable.
Try different monitor.
Do you have a graphics card installed? Remove it and see if that resets. This system has a BIOS option that controls which video device to prefer on boot and it and may be set to the graphics card.
This machine was probably manufactured around or before 2010. It's possible but unlikely this system was affected by capacitor plague and may have one or more swollen or busted capacitors. This requires resoldering new caps or replacing the motherboard.

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