Alcatel Pixi 7 Tablet Not Turning On, Battery Check and Button Combinations Tried

Hi
Recently, I got a malfunctioning Alcatel pixi 7 tablet (it was once added in orange as a free contract).
The tablet does not turn on and does not respond to any button combinations.
I thought the cause could be a battery (the tablet has been unused for over a year).
I checked it and removed it from the device had a voltage slightly exceeding 2V, after charging with a charger to 18650 it is 4.15V.
The tablet only reacts when connected to a computer (the computer makes a sound of connecting a new device and after 2 seconds of disconnection, the tablet displays nothing).
I have no idea what might be broken.
I will be grateful for all suggestions.

Hello kusiu2 - how did you deal with the problem because I have similar symptoms?

After a very long period of non-use, you need to start with a "solid" charge of the batteries.
Turn on the tablet to charge it for at least a few hours.

The battery was good.
I powered the tablet with an adapter with the same adapter as the battery and still nothing.
I gave up repairing this device.