Replacing the battery isn't very hard to do. It is mainly removing screws, opening the case, and replacing the battery. Posted below is a link to the ag leader instructions to replace the battery. You can order the exact replacement battery from agleader. I have also ordered the battery from ebay using the part number printed on the battery. When I did this I had to cut the connectors off both packs and put the old connector on the new battery pack.

https://support.agleader.com/kbp/index.php?View=entry&EntryID=28