At the risk of me repeating a lot of post please refer to: https://eu.community.samsung.com/t5/tv/smart-tv-continually-restarting/m-p/180334#M1844
I too have a UE40D5520 and it has started a bootloop – continually
Samsung support say this does not effect my TV – it does
It is out of warranty so they will only help for a charge.
This is obviously a design flaw – has anyone: looked at a legal route to get recourse or better still to get Samsung to acknowledge and issue a fix?
its c2012. From the other posts I referenced and the searching I've done this seems a common issue with Samsung. Does anyone know if you can boot from USB without access to the menus? Is there a reset sequesnce?