Toshiba TV Issue: No Picture

Hello,
I have a problem with my Toshiba TV (LED Backlight), I no longer have any picture.
A few days ago, there was a kind of "white screen" that started from the bottom and moved up to the top in about a second (a bit like an animation), then the entire screen remained completely white.
After turning it off and then on again, the screen stays completely gray with irregular clusters of black pixels...
Nothing changes, no menus appear with the remote, I've tried switching outlets or turning it on without plugging in any HDMI cables, but nothing changes...

I bought it less than a year ago at Boulanger and took an extended warranty, but my father had the bright idea of throwing away the receipt...

I would like to know if there's any way to repair it somehow (replace a fuse or I don't know what), I'm taking it back to Boulanger tomorrow just in case, but without a receipt or proof of purchase, I doubt they'll do anything...

Thank you in advance.