The strange fact is that it seems to power on and off, I mean, I press it once and the led lights green, then blue, then green, green, green etc, then I press it again and it doesn't light, as if it turns off.
and, @ david_e, it doesn't seem unfair to me at all to go to the shop, because it's not normal that a device freezes or bricks while restarting after an update, whether it is sideload or not, because when the Kobo updates the firmware via wi-fi it's the same thing: it downloads the firmware in the folder and then updates, I guess.
Now I'll try to fully recharge it, as someone said.
I never charged it before, so I don't know whether the led lights or not during charge, I wouldn't recognise it charging.
Do you think they'll eventually fix it if I use my warranty?
Sorry for my bad english