Hi, @MalibuArt
Thanks for posting, and welcome to the Roku Community.
We understand the issue you have encountered with your Roku devices, which are going to a black screen. We're here to assist. We'll provide you with steps and instructions to resolve the issue.
First, we recommend changing the HDMI port where you connect the Roku Express 4K. You can also plug your Roku device directly into a power outlet to ensure proper power setup.
If the issue persists, please proceed to factory resetting your Roku devices to resolve the issue.
Using the physical button
Located on the back or bottom of your device, the physical Reset button is either tactile or a pinhole design that requires a straightened paperclip. It will appear similar to one of the following:
Once you locate the Reset button and your Roku device is powered on, press and hold the button firmly for about 10 seconds. When the factory reset is complete, an indicator light or status LED will blink rapidly on most Roku devices.
After a successful factory reset, your Roku device will restart in the same state as a factory-new device, and will be ready for you to re-active the Roku devices.
For more information, you can visit this support article on How to system restart or factory reset your Roku streaming device
We hope you find this information useful, and feel free to reach out to us if you have further concerns or inquries.
Best wishes,
Kash
Takashi O.
Roku Community Moderator