The screen of my e-reader is stuck.

Hello,

I have a Kobo e-reader (FNAC) that I've been using for a few months, and everything was fine until today, when I turned it on: my screen is frozen, the FNAC logo is blurred, but the touch still works, although everything is unreadable.
This has happened to me before on a handheld console, but unlike the latter, I haven't dropped my e-reader.
I searched online but didn't find anything, except for some discussions suggesting it might be the battery, but that's not the case for me.
If you could let me know if there's a solution and that it doesn't need to be repaired, that would be perfect!
Thanks in advance!

Configuration: iPhone / Safari 7.0

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