Help for car seat safety!!

[Aprilmum1]

3 times in the last 4 days, I've discovered my partner has not correctly buckled DC in his car seat. DH forgot to buckle or tighten down the straps. PLEASE, what tricks can I have him start using to double check that everything is done correctly?

(Currently pissed beyond description, but realizing being angry isn't going to help.)

Are there any shocking videos of crash test dummies you could show him?

You really shouldn't need to do anything I'd be very angry that my child's safety hadn't been taken seriously and would be very tempted to not let him take them in the car with me. On a more practical suggestion, note stuck to the steering wheel to double check?

Start unclipping his own seat belt when your in the car with him and tell him if it’s good enough for baby then it’s good enough for him. Well just sat it to him not do it.

Have you asked him why he thinks what he is doing is ok?

say not sat

Oh, I let him have it. I know he is mortified by not clipping the baby in right. One time, I understand humans make errors, but three times?!? That's just carelessness.
I'm looking to see if there are any apps or gear that could help us. (I don't really want to buy a whole new car set though!) Most are for not forgetting baby in car, which we'll be taking extra precautions against also.
I suggested a note on the steering wheel, but it's easy to get used to and ignore after a while. I also thought of having him text me a photo of the baby clipped in every single time.