If the compressor is running and you are not cold enough there's only a few options to check.
1st- you've changed the adaptive control board? And the thermostat, both up in control box in fridge.
2nd- if those parts are new you'll need to pull rear panel of freezer and check frost pattern. If the compressor is running more than 15 minutes there should be frost on the evaporator.
3rd- Your IM will not cycle above 15deg so that may be a clue. Most items will not indicate melting point until 32degrees, but ice cream softens about 15 deg due to fat content.
4th- look for ice/frost build up anywhere in that freezer. Specifically the bottom or heavily frosted at rear panel.