Freezer has frost on back wall, fridge not cold enough

freezer has frost on back wall and not feeling to cool ( ice bag completely melted)…refrigerator not cool as it should be (i wouldn’t eat anything out of it now)… any ideas? not too long ago i replaced the solenoid for ice maker water running to long…hope i didn’t screw anything up with that, but it went smooth anyway. i’ve heard it could be defrost timer, defrost heater, or defrost thermostat…how to choose…hmmmm…HELP please…thanks

i have now taken the false wall out of the inside back of the freezer…the coil was completely frozen over…i thawed with a hair dryer…any further ideas on what is next would be greatly appreciated. i know that it will only be about a 2 wk fix from what i’ve been able to find on my own, however i don’t know what to do next, or what to repair.

yes it is blackened…or greenish black in color…but i had already plugged it back in to test the piece that clips onto the coil…don’t really know what that is…i’m guessing it is the thermostat defrost…to see if it makes a noise or if it is overheated or if it even tells it to defrost…the coils have frost covering them and waiting to see if it defrosts or continues to frost. would that be a logical step? or i’m guessing here…if it is blackened the heater is bad and i should just replace that and see if the thermostat is bad later or replace both.

I would replace the heater, the thermostat most likely is good.

thank you very much for your assistance…you have saved me…you guys are great.