The TV seems to be stuck in a firmware update loop. It get stuck before lunching any options menu.
Basically I tried the following: I tried simple shut down (from hours to days) and restart. I tried unplugging (for hours to days) and plugging it back. I tried the reset (factory) button from a few second to minutes.
I read that this might have to do with a firmware update issue and that there's a way (USB key) to manually update the firmware. Could that help?