The Skoda Yeti battery was almost at zero. We tried for 10 minutes to start it using the device (while pressing and on the boost). As a result, we almost gave up, but decided to give one more chance. As a result, they launched on the first retry. I just didn't have to wait long after the boost. If you pressed it and the green does not blink, then try to immediately start the engine. It worked for us. Something like this.