Accessories PW3 - it's the battery or the Fw ?

Hi
I don't understand, but i have a PW3 from 2015.
in 2017 i stop to use it so the battery go to 0% for many months.

then when i turn on it, the battery go down from 100 to 0 in few hours (10 hours from 100 to 0 in stand by! )

then i buy 2 battery, one directly from aliexpress and one from ebay.

nothing to do, the battery, the 2 new battery, go down from 100 to 0% in one day....

in your experience, there are all 2 my battery fault, or it's kindle FW ? 5.11.1 (the last)

can i try to buy another battery?

thank you a lot!