Kindle Reader Non-Charging Battery: Reviving & Troubleshooting After Long Periods of Disuse

Hello,
I have such a reader, little used bought from a store. Everything was great all the time, but I didn't use it for two months. The screen showed "picture" that the battery is low and you need to connect the reader to the power supply. I connected with different cables to different chargers, computer and still nothing. During the first charging, the orange LED was on, after a few hours it turned green. However, there is still a low battery symbol on the screen and the reader cannot be turned on. The contents of its memory can be checked when connected to a laptop and it works. I can not make any measurements, because this reader seems to be non-removable, no screws or latches.
What can I do to bring it back to life?
Ps. I noticed that after connecting to the power supply, the LED lights up in green, but after disconnecting the power cord, the LED turns off after a few seconds. I guess that means the battery is not charging. What to do with this.

It is demountable - type in Youtube open kindle and you even have videos on how to do it.
Probably a damaged battery - I have already replaced two pieces that would not charge and turn on.

Thank you very much for help. I've already opened my kindle. The battery is dead. Now he will look for a replacement and give him a second life.
Thanks again and best regards.

Added after 2 [hours] 48 [minutes]:

Welcome back,
The fact that the battery was dead was assessed by my friend who deals with electronics a bit. He took out the battery and gave it to me to buy a replacement. However, before throwing her out, I asked another friend to diagnose her. It turned out that the battery is charged and it has 4.2 V. I know that the voltage often does not mean that the battery is good, but I tried to put it back in the reader. And what was my surprise. The reader "came to life". I connected it to the charger again, but the LED is green, which means that the battery is fully charged.
For now, I'm using the reader and it's OK.
However, I do not know if the situation will not repeat again or it was some lack of contact in the device.
In any case, thank you again for your help opening the reader.

In my reader, no battery (old, new, completely different from another device but 3.7V) does not want to charge. The old battery was charged with another charger to 50%, the reader turned on, the LED lights red, there is a message that the battery is being charged but the battery is only getting low. I've tried several chargers, several cables, I have a USB meter and a voltmeter and ammeter built into the USB cable that show voltages of 5.1V - 5.2V but 0A.
The voltage on the battery connected to the reader (during charging) is as much as it actually has, while the power button shows 5.1V.
The strangest thing is that after disconnecting the cable from the charger, the USB meter shows the battery voltage in the reader. No device does such a thing, always the UBS meter goes off when disconnected from the charger.