I read the manual, and nothing indicated, otherwise there is a stack, I decided to look on that side, I remove the sticker on top of the tablet (quite difficult to cleanly remove) below there are 4 tiny screws, I take them and I see that the battery is wrong !!
I put it back in place, I close everything and now everything works fine. So good news, we can replace the battery, although apparently it is not expected.
If the tablet had worked right away, I would have put 5 stars.