Anybody help me? Customer support hasn't helped me at all

I've had issues with my elgato, can get screen on monitor but not my computer, says connect a device, tried multiple ports and cables. I've spent the last month and a half going back and forth with cus support and they havent even tried to give me any possible fixes. Goin on about warranty options, even though it's a 6 year old device so it's literally worthless for me to do that. Complete waste of time. It's been taken complete care of and there shouldnt be an issue as its showing on my screen. Anybody have any possible fix? Even just a "try this"? Elgato hasnt even tried to do that for me. It's an elgato HD