Freezer not cooling in my FB3921

[Hamiltons]

I was having a knocking sound in the fridge/freezer (Samsung residential). After reading some articles I did a forced defrost. The sound went away completely after resetting the unit. No longer knocking but now my freezer isn't cooling below 40 degrees. Is this something I can fix at home?

[riflegunbuilder]

I had a problem with mine not freezing. Found that the handle was loose and had shifted just a little and was holding the door open just a tiny bit.