you said it "still just gets very cold", if its too cold in refrigerator, your problem is not a defrost related issue, so I hate to point out the obvious but you wasted money on those not too cheap parts.

Why dont you instead tell us everything you have noticed and performed, be as specific as possible, and include any and all small and possibly unrelated symptoms. Only then can we help you perform refrigerator repair

FYI, my Chicagoland refrigerator repair house call charge would have cost you less then what you spent on those parts

that heater is on an A/C circuit, which means it does not matter which terminal you plug the blue wire or pink wire into, front or back or vice versa. If it wasn't working before, then you didn't have the plugs in securely.

Remember too, we are trying to help you, FOR FREE, so check the attitude at the door.