9.5x2 Scooter Inner Tube, 9.5 inch Tires Replacement, for Niu KQi3 Sport/Pro/Max Electric Scooter [Thickened] [Valve Extension] [Tire Levers] (2 Pack)

https://a.co/d/09gOQFaq These the ones you used too?

Likely it’s the tube that has a tear or a pinch flat. I’d recommend changing it yourself if you can get the tube from niu (which would take a while) and get some tire spoons and learn to change the tires. There’s not many tutorials of how to do it online and I only saw one in German, but it’s fairly simple to do, just a little time consuming. If niu doesn’t send you a tube, the one you can get on amazon is fairly cheap, just look for a 9.5x2 inner tubes, these are the ones I got: https://a.co/d/09gOQFaq The kit comes with a couple spoons, but you should get a set of longer wider ones, way better leverage.

Something similar happened to me (pinch flat). Replacing the tube is a bit of a hassle, but it’s doable and relatively simple. These are the tubes I used, and you should definitely get some tire spoons as well. It takes a bit to work the tire off and to install the tube, but once you do it a couple times it becomes second nature: https://a.co/d/07F2QHWZ