Do you happen to know the dimensions of the battery? I know the thickness will be off considering yours bulged, but the length and height would help search for a new battery. I have been seeing a lot of batteries on aliexpress that “look” like the size and capacity of the Cube i9’s battery. The only difference would be the voltage. Most batteries I am seeing are normal 7.4V, essentially two 5000mah lipo’s in series. I know that it states 7.4V, but wouldn’t a fully charge lipo get the voltage up to 4.2V per cell, thus giving the 8.4V that the stock battery references?