If your Lynx Solar is not responding or waking up it may have powered itself off. To correct this please examine the back of the camera unit. You should notice a button on the back. Press and hold this down for three seconds. When you release the button the camera will go through its power up process.
Within 30 seconds your camera should be available to you within the app.
If this hasn't resolved your issue please submit a help request from the ? Support button to the bottom right.