Sorry, your report brings some misunderstandings here.
If you can use the keyboard&mouse passthrough feature,
it means you can start our APP with no problem,
or you can't activate this feature.
Please answer the following questions as many as possible,
so we can provide better support for you.
1. your console and game
2. The color and state(breathing or stable) of the LED indicator on ReaSnow S1 when you are in trouble?
do you hear any continuous beeps? how many beeps do you hear in one cycle?
3. Which peripherals are connected to ReaSnow S1? please provide the specific model and producer.
PS: All peripherals should be connected to ReaSnow S1 first, before connecting it to a game console.
4. a video to show us your trouble(!!!)
please upload the video to youtube or other file-sharing servers, and send us the URL.
And the following might also be some help for you:
ReaSnow S1 Quick Guide
https://youtu.be/CFdJpR5Zj0AWarning and Solution
http://www.reasnow.com/download/ReaSnowApp/Warning%20and%20Solution.pdf