Recently ran over half a 12mm wrench which put a nice hole through n through, scratching my rim. Have just replaced the tyre and went for a cruise to wear it in and my partner noticed the hazards flashing (I don’t even know how to turn them on haha) from what I’m googling it says possible speed sensor issue. Does anyone have a manual they could send pics of on that section? Please and thank you 

Is it still doing it after being switched on and off?