Remove power and defrost. Check heater element behind panels in back of freezer. With ohm meter should read 20 ohms or less. You could remove it and bring it to a local repair shop and have them test it and if required order you a new one. If this does not work it may be the control board
To properly charge that freezer the system needs to be put into a vacuum to below at least 500 microns. Did you fix the leak? The only reason to put refrigerant into a system is if it leaked out. Also it has a critical charge and must be weighed in with a scale in onces. If it says 16 oz. It will not work right if you put in 15 or 17 oz. If you did all these things the only thing left is to replace the cap tube drier assembly or the temperature control. Hope this helps and good luck.
