Keeps getting warmer until power cycled. Then gets to proper temp then

I have a Samsung bottom freezer Model rb215labp. Display on front doesn't seem to display right, it will always display what it's set to -25c and 1c. When fridge is first plugged in it will cool to proper temp then over 24hr period it will slowly warm up. 24hrs later Ice cubes are Melting and fridge is at 9c. Seems like if I unplug and replug fridge it will cool to proper temp then slowly warm again.

Fridge is 5 years old. This is what I've tried:

Opened access panel on rear and cleaned all dust build up(not much), fan between condensor and coil is running constantly. Condenser can be felt and heard running

Removed panel inside fridge and fan is running when door trigger is pushed. Coils were room Display on front doesn't seem to display right, freezer is cold but fridge is warm. This is what I've done so far...

Opened access panel on rear and cleaned all dust build up, fan between condensor and coil is running constantly

Removed panel inside fridge and fan is running when door trigger is pushed. Coils were room tempature and no ice or water was noticed, drain wasn't clogged, water ran straight down to bottom drip pan. Unplugged and replugged fridge. Waited 15min and the coils began to frost like expected.

This fridge has two coiling units so next I Removed panel in freezer and it was just as clean and unfrozen as the fridge. Freezer coils also had just started to frost. Fan in freezer also worked as expected. Water rain from drain directly to drip pan.

Checked error code on display and it says c-fan

The condenser fan is running fine. Removed main board and unplugged replugged all connections and checked board for broken solder points or burn marks, everything looked good.

Why will it work great to get to proper temp and then start to warmup? Why aren't the two Separate temp sensors showing the proper too warm readings instead of what I set the fridge to? Main board wacky? Thanks for the help