A:Answer Most often this means the light bulb needs changing.
However, the light bulb is no longer made, and is not in stock in appliance repair centers listed on the web or around most towns.
As to how it is that Best Buy and Lowes still sell this model, year after year, with the rotten light bulbs, and no hope for replacement, I do not know.
I guess they don't know, until enough of us tell them.
Buyer beware This model of microwave has light bulbs that go bad within a year or two, and there are NO replacements, no other sources, no substitutes.
Don't buy the SMC1452CH!