This was a replacement battery for my DC35, whose original battery's life is now down to 8 minutes or so. This new Chinese one lasted 5 minutes, stopped, and hasn't worked since despite being charged up overnight. So back it goes.
Amazon instructions don't say how to return it, other than "don't use the postal service". I'll find out tomorrow (by going to a post office) whether this is bollocks or not but meanwhile, anyone had to return a similar battery and how did you do it?