Intermittent signal from Intensity Pro 4K

Greetings.

We have an Intensity Pro 4K card running in a Sonnet Express housing connected to our iMac.
Following the tropical storm last week, now the card/signal is only intermittent and I'm trying to determine if it is the Sonnet Express box or the card.

One theory which seems to be most probable is the card is overheating and shutting down -- then when it cools enough, starts back up again. Yesterday when we were looking at it during a time of not working, looking at the rear of the Sonnet Express box, we could see lights on inside but the blue signal light on the front was not illuminated. This morning when someone was in the equipment room and the card WAS sending a happy signal, the blue signal light was ON.

When we are not getting the signals from Intensity Pro, if I open Desktop Media, I can see the card but it is not active. If I open Media Express while I am not getting anything into Wirecast from the card, there is nothing. We use the Intensity Pro 4K to bring video and audio into the iMac and when we have the black screen (not working), we have neither audio or video. The audio and video are coming from different sources. Also, Wirecast sees Intensity Pro even when it is not sending a signal.

So, in anybodies experience, does that sound like the Sonnet box or the Intensity Pro card acting up?

Thank you all for your time and expertise.

Often you can only trouble shoot by substitution (not always practical).

You can check/try the easy stuff first.

Unplug the box, uninstall Desktop Video, reboot, install latest version of Desktop Video.
Re-connect the box and try it.
Reseat the card in the PCIE slot.
Replace the TB cable.
Try a different Mac.

If there was a power surge then I'd be looking at the PSU on the Sonnet box (best guess).