Hi @SG111 you do not name the model but just check you have the latest firmware on Samsung support https://www.samsung.com/uk/tvs/ Are connections/cables secure, have you disconnected Tv and tried again, best to leave around 5 minutes. However it does not look promising with a loud buzzing noise as well, may well be a power board issue. I would not suggest trying to fix a power Board yourself if other troubleshooting fails. on other other thread you mentioned additional warranty via rgb, noticed on current available models the warranty via customer registration.
I do not work for Samsung or make Samsung Products but provide independent advice and valuable contributions.
My Device- S21 Ultra 5G ( SM-998B/DS ) CSC= BTU , 12GB/256GB One Ui 5.1,Android 13 .