What does the error mean?

Error code 25 indicates a faulty signal from one or both brake levers. It can also occur if you pull the brake lever while starting the scooter. 

How can the error be fixed?

First, check whether the brake lever handles are loose. If they are, carefully tighten them with an open-end wrench. Next, check the wiring between the brake lever and the display. If everything looks fine there as well, the brake lever will likely need to be replaced.
If the problem persists,please feel free to contact usat oryour dealer.