If it's serviceable they will just swap out the panel or LED's (or both) depending on the TV, I would imagine. I once bought a TV that had a panel issue along the bottom inside the first year, they swapped out the entire panel. Samsung's were also fairly notorious for the capacitors on the power board dying leading to sets not switching on (just clicking) but I expect they will have sorted that by now, if not though a faulty power board could cause all sorts of different issues.
If it's not serviceable and in warranty then I expect they will just replace it with something roughly equivalent.
I've had nothing but issues with Samsung capacitors over the years. I believe they must be using cheap parts on their panels. I've had 2 TV's die because of it outside warranty but within 5 years (one LED, one Plasma). On my 3rd Samsung TV (QLED) i took 5 year extended warranty because I fully expect it to die within 5 years like all my other Samsungs. I will not buy another Samsung TV for a very long time, I've been super dissapointed by them - not just their TV's but phones as well. I've come to the realization that Samsung is a cheap brand using aggressive marketing to make itself appear like a high end brand. Meanwhile I've actually also got a 7, almost 8 year old LG LCD TV and this one has never had a single issue and still going strong - putting Samsung to shame!
edit:
Just remembered about my experiences with PC monitors. I've still got, but rarely used anymore 10 years old 23 inch LG LCD monitor - again no issues at all! About 6 years ago I bought a 4k Samsung 27 inch LCD monitor, the panel had major defects out of the box and had to go back - I just asked for a refund. My main PC is now using a ASUS monitor.
In summary: Samsung uses cheap components and has cheap quality control