This is the most frequent symptom. The TV turns on, displays the logo, and then restarts repeatedly. This indicates a corruption in the system partition of the NAND memory. Re-flashing the firmware often overwrites the corrupted sectors, restoring stability.
If you successfully revive your device, consider installing a lightweight launcher (e.g., "Rootless Launcher") and using it exclusively as a digital photo frame, e-book reader, or dedicated MP3 player.
To flash this firmware, you need specific software depending on your CPU: