Sony android TV in endless bootloop

Hi

I own a Sony TV model 65W850C, when I turned on the TV today, it was blinking in the menu to choose which optin /device to watch, so I reboot the TV. However, it ended up rebooting endlessly.

I tried hard reset by pressing the power plus volume down buttons and turned on the TV, released the buttons when green light appeared, that didn't help. I also tried to uploaded the firmware through the USB port, that didn't help either. I read this is well known issue but there is no solution I can find. Anyone out there managed to fix the fault?

Thanks

Andrew