You'll see an error code on the display. 1E

Samsung could have shown PF (for power failure), but in keeping with a philosophy of obfuscation and keeping service outfits busy (you'll pay someone to "reset" your refrigerator). Here's what to do.

Press the ENERGY SAVER and the LIGHTING buttons (not really buttons but touch panels) simultaneously. This will take a large hand (I found it will work also with two hands, but not reliably). Hold this button press for about 10 seconds, or until all the segments on the panel light up. That's your reset sequence. The unit is now ready to test.