HDMI not working when trying to play Xbox saying no signal is it on

So me and my fiancé sold our second console and right after we did it our Xbox stoped working with the hdmi. We even tried our PlayStation and laptop.we think it might be the hmi but  we bought this hmi not even 6 months ago and it’s been working fine every day until the other day. I have the onn Roku tv. And we’ve tried every port