I’ve bought a swifty e-bike as a cheap introduction when my legs got too old for the hills of mid Devon. All fine for three years when the controller failed, all mode lights flashing. With no help from swifty I started looking myself and found a big spark when connecting the battery and my controller fails after about 30 seconds, if I then disconnect and then reconnect the battery immediately then no spark and everything works. I understand discharged capacitors causing the spark but why does it cause the controller to fail? Any ideas or experience of this?