Hi, can anybody help I am still getting used to my haibike still under 100miles wilst out on a ride today after approx. 10 the display showed er15 the bike still worked ok , I removed and replaced the display and adjusted the magnet on the rear wheel to no avail. But after stopping to visit a friend for about 30 mins everything returned to normal it has been suggested I change the battery in the display?? any body else had this problem????