Aura Frozen on "Low battery level", impossible to start

Hello everybody,

I have my Kobo Aura for more than 2 years, I upgraded the firmware normally with wifi (including in January 16'). No issue up to yesterday.

Now it's frozen with "Low battery level" message ("0% remaining"). I tried everything:
- load it for several hours on USB port on my computer, with wall charger
- push the light button and try to turn it on
- push the reset button with a paperclip
- a lot of combination of these solutions

Nothing happens, still blocked on this screen. Any idea?

Thank you!