i purchased a used spark that appeared to only be used a few times. The Ground sensor stays on and only reads about 19 feet when it is clearly above 100. It will sometimes bounce back and forth between the ground sensor and gps height! I have tried factory resetting and it still does the same thing!!

Update today I was flying at about 300 feet taking pictures and as I came down I could hear it way before I should and as I looked up I saw the spark coming down very rapidly I put full throttle up and it never stopped and slammed into the ground! Luckily it still works but the altitude doesn’t work properly. I have had it descend rapidly before and throttled up to save it!! This is frustrating