My 4 year old samsung un50ku6300fxza tv is stuck on boot loop at smart tv screen

Hi, Team thanks in advance.

My samsung UN50KU6300FXZA is stuck on boot loop at smart tv screen. Tred plugging in different power sources but still no luck.
ordered new motherboard for audio and video from shopjimmy and swapped it. but still the problem persists.

Need your guidance in fixing it.

this tv used to work like a champ until a week ago but It started having issues when I plugged it into a power socket extender along with ps4,ps3...