This is a tough one.
I think that the problems arise from all of the if statements instead of using else if statements.
When you have a series of if statements and they are all true, then the all get executed. if you have a series of if and else ifs only the first true one will execute.
The student may need to go back and think about if he/she only wants some of the actions to happen. Like, I can push the cars when I have the score (2, 4, 6, 8, 10, 15, 20, or 25) but can I also trigger game over, right now that happens.
Hope that makes sense and is a start. Please continue to update the progress.