Is my refrigerator on a "defrost cycle" or did it malfunction?

(I have zero experience with “defrost cycles”) My GE refrigerator is 18 months old and past its warranty. It has the freezer below, fridge on top. When I open the fridge door, there is a digital display for both the freezer control and the fridge control with clicker ons to raise and lower each respective temps. The digital displays read in Fahrenheit with a selection range approx of -6 to +8 degrees for the freezer and approx 34 to 43 degrees for the refrigerator. Is says suggested range 0 degrees for the freezer and 37 degrees for the fridge. I came home to it yesterday and there was lots of frost on the outside of items in my freezer such as ice cream and bags frozen vegetables. I checked the digital display and it read 20 degrees, which is outside of the adjustment range. The fridge read 48 degrees also outside of the adj range. The frozen items were softer than normal. I tried to lower the temps for the freezer and fridge with the clicker ons. The temp for the freezer dropped from 20 degrees to 0. I closed the door and a few seconds later it was back to 20. I tried again and also tried to lower the fridge temp from 48 to 37. after I closed the door and seconds later it said 20 and 48. As I’m writing this I realize it snapped back to 20 and 48 because those were the current temps and it may have been lowering. But at the time I didn’t realize this so I took 2 screws securing the display and there were only 3 wires going to the display circuitboard. I disconnected the 3-wire plug and plugged it back in and the freezer display stayed at 0 this time. The fridge wouldn’t go back so I put it on turbo-cool function. I came back to the fridge 2 hours later and the fridge was at 9 degrees. This morning it was at -1 degrees. The fridge seems to be back to normal too. whats up?