Neighbors have a computer that won't work after a lightning strike.
With the video cable connected, the monitor stays black and in the
standby mode. There are howls from the speakers, like feedback. With
the cable disconnected, the monitor will briefly show a notice that it's
not connected. There are no howls from the speakers although the mic
cable remains connected.

With the power off, I checked the pins of the monitor cable to see that
the grounding pins were grounded and the signal pins were not. One
grounding pin is open, so it seems certain that the monitor is damaged.

The next step would be to try another monitor to see if there's other
damage to the system. In case the computer's video card is damaged, can
a monitor be damaged by plugging in to it?