If you know your HTC VIVE Focus 3 is charged but is not responding, a manual reset may be necessary. This may also require a re-install of the PeriopSim VR App
There are three ways of resetting the HTC VIVE Focus 3 headset:
To initiate a software shut down. press and hold the power button for 3 seconds. Important: Manual shutdowns will cause all unsaved data to be lost.
If a software shut down still doesn't turn off the headset, you can press and hold the Power button for 10 seconds to perform a hardware shut down.
Lastly, a full factory reset reverts the headset to its initial state—the state before you turned on the headset for the first time. Important: Factory reset will remove all data from the headset, including apps you've downloaded and installed, your accounts, your files, as well as system and app data and settings. Be sure to back up any data and files you want to keep before you do a factory reset.
To perform a full factory rest of the HTC VIVE Focus 3:
Go to Settings > Advanced, and then select Reset. Select Erase all data.
If you need to reinstall the PeriopSim VR app after a factory reset, follow the below links -
Installing PeriopSim VR for HTC Focus 3
Installing PeriopSim VR for HTC Focus 3 Without an App Store