Anytime there is an issue like this, it is almost always the PC which is the issue. It could be that HDMI Hot Plug is not turned on within the projector's menu system, or may not even be available.
Hot plug detection will recognize the laptop when it is plugged in and initiates the HDMI video communications between the projector and the laptop.
I can't imagine a situation when this really shouldn't just work, but I've seen from my laptop some issue with hot plug not working, and in those cases I sometimes have to manually tell my laptop to start broadcasting video.
With a Dell, I press Function+F8 and it gives me options to mirror my display, or extend my display, or just use the external display.
So, you want to be sure that your laptop is properly outputting video and sees the external display as an option.
A big issue is when a external display (projector or monitor) is not automatically detected, that end users don't know how to configure their laptops to connect to that external monitor manually.
So, watch these videos, and see if that is of any use (it may not be)...https://www.youtube.com/results?search_query=connect+external+monitor+to+laptop+windows+10+
It is also entirely possible that the projector's HDMI is not working properly and is just busted. Hey, it happens. HDMI has a finite lifetime of use as do projectors, so it may have just gone bye-bye.
Let me know.
- Theater, whole house audio, and technology consultation during the build and installation process in the Washington, DC metropolitan area.