To fix your laptop's HDMI port, ensure it's the correct input on your display, try a different HDMI cable and a different display, and check for physical damage to the port. If those fail, update your graphics drivers in Device Manager and try to project to a different display to determine if the issue is with the laptop or the display. 

To receive assistance from Dell chat support, they need to verify the warranty status and ownership. Then you must troubleshoot with them.  Click the "Get Help Now" icon on the right to start a live chat session. If already out of warranty, click here for the Dell out of warranty offering.

he two devices are new. The shipment included about 15 devices, but only these two have the HDMI issue.

I tried everything: reinstalling Windows, updating drivers, testing with multiple HDMI cables and different screens — nothing worked.

However, the USB Type-C port works without any issues.