In the KSSC48QM and earlier versions "SHOW ROOM" mode was fairly obvious because the user interface display just cycles the display through all it's indicators - and, of course, the compressor never comes on.
In the KSSC48QT and brethren ... not so obvious! "SHOW ROOM" mode is entered and exited by holding "MAX COOL" and "POWER" for a few seconds. Everything acts normal except:
1. Compressor never turns on.
2. You CANNOT enter diagnostic mode.
Don't replace this $9000 refrigerator because the control board is NLA and it happens to be programmed for "SHOWROOM" mode!!!!
We're seeing a lot of these controls come thru the shop these days, almost always with real problems, but once in a while the re-installer gets stumped by inadvertently entering showroom mode.
Happy New Year to y'all!