If you have a Samsung Smart TV (model UE40D5720RS) stuck in an endless boot loop — showing HDMI or the Smart TV logo and then restarting — you're not alone. This issue is often caused by NAND flash memory degradation, which prevents the firmware from being read correctly at boot.
Place an ice cube wrapped in cling film directly over the main NAND flash chip (labeled IC1300) on the TV’s mainboard before powering it on. Cooling the chip stabilizes its read operations just enough to let the TV boot normally.