I'm thinking you could find a same technology battery within 0.1 Volts and the same or double the AmpHours and then wire it to the old battery terminals. Then carve up some plastic for a new battery holder and craft that with heavy packing tape and Gorilla Glue.
Sorry if this seems harsh but why lose your toy over a battery?
company is out of business i guess and i need a battery for my reader. please help