It sounds to me as if the reporter got it garbled, confusing "screen burn" (definitely visible to users) vs. burn-in failure, which is a yield problem (and thus invisible to users).
"Burn-in" is just a test stage in electronics manufacturing. Since many failures exhibit themselves early in the product life, "burn-in" attempts to accelerate product aging in order to weed out the lemons. The product is run for a period (could be hours or days) at a simulated accelerated rate of usage, often at an elevated temperature. A "burn-in" problem says nothing about specific failure models; just that the yield is poor. This inevitably means even more testing is called for, rate of production is reduced, and the cost of manufacturing is excessive.