He used alcohol to self medicate to the point of addiction... How do I convince him to get help?

My partner of 4 years has been had an alcohol addiction all that time. He turned to liquor to self medicate. He has depression and anxiety that makes him numb/bored, and he has self hatred. He needs medical professionals, but he has been to rehab in the past (in his teenage years for something else), seen counselors, been on a few kinds of meds, and he insists there's no point in those efforts. That they don't work so its not worth his time.

I am mentally I'll myself, and I try to tell him that mental healthcare is a process and takes patience (which he actually has a lot of) in order to find the right mix of treatment. He needs the help, or he is just going to turn to some other substance and I'm afraid it will be worse than alcohol. How do I convince him to get help so he can sustain happiness while sober...