If the camera can connect to WiFi, refer to this article.
The camera may have a physical problem.
If you are desperate and planning to throw it away (into the trash) and have the mental energy to keep going, you can try putting the camera into developer mode and refer to my experience:
The technique above may make the camera even more unusable. It is your decision. I’m just sharing what worked for me.
adb shell
reboot bootloader
You can apply for the developer partner program here:
https://www8.webcas.net/db/pub/ricoh/thetaplugin/create/input
This is primarily useful if you are an Android developer or have a friend who is an Android developer. If you or your friend do Android development, then you will be able to assess what adb shell does and also the bootloader.
In my situation, the camera would only stay up for a second before it completely shutdown, so I needed to run the two commands immediately after I turned the camera on.
I do not recommend the above technique as it is long learning process if you are not already and developer. Also, it may make the camera worse.
I’m just sharing my own experience.