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If Samsung will not repair or replace their defective product and they claim the warranty is expired, then you can sue them under product liability
law as an alternative legal theory to breach of warranty.
You would need a local consumer protection attorney to file suit against Samsung under product liability law and legally if the product is defective in manufacture or design, then they are liable for their product if you discover the defect within 3 years and file suit within that time.
You will need to have a report from the technician as to why the TV is defective.
You can also report this to the Consumer Product Safety Bureau as they investigate defective products and can mandate a recall of the product if they find it is a design defect, which could cost Samsung millions. So in your letter to Samsung demanding replacement with a different model of similar size, you need to inform them that if they refuse to settle this matter, in addition to legal action you would be filing a complaint with the Consumer Product Safety Bureau and seek a national recall of their defective product as well.
You do have a right to a product free of defects and when they replaced the product, while they do not have to extend the warranty for another year on the replacement, they are indeed liable for defects in manufacture or design as long as you sue within 3 years of discovery of the defect.