How to replace it
1.Cut off the plastic cover to take the original pack out.
2. Use a long nose pliers to tear the contacts off.
3. Put the new pack into the plastic cover to make 2 marks on it, +&-. Please note, it must be correct direction when you put it in.
4. Solder the contacts on the new pack, just make sure the contact points must be right on the +&- marks you just drew. Tin the contacts before you solder them on.THE BETTER YOU TINNED, THE FASTER YOU SOLDER.
5. Insert the finished pack into the cover, make sure the contact points are just at the correct position.
6. Wrap it. Done!