Late reply but I had the same issue on my xbox one x too. Its the hdmi ic timer chip which can be repaired for about 50 quid or at Home if you know how to solder.Perfect time for my Xbox one X to have HDMI port issues I can hear it boot up and games load in my headset but no signal picked up by any tv I have - plus cable swaps and endless reboots.
Out of warranty, so might just pick up a One S all digital version as it looks like it will cost similar to fix including postage and all that. Especially has I have the Series X preordered anyway.
No Warzone for a good few days, nightmare.
Personally I bought a new one X from John Lewis as I don't see many repair shops opening anytime soon.
If you really fancy some xbox though there is a way to stream to your laptop using Windows 10 companion app.