I’m at a complete loss...

I just don’t know what to do. My younger brother who is 28 today is clearly having some sort of mental issue. Last night he called to curse me out. (For showing up to my parents house with the key I have and after I texted him I was on my way over. But he felt that I just showed up) he then went on to tell me he barricaded himself in the basement because he thinks the noises of the house are people trying to get in. And that’s all my fault he is paranoid. Of course I tried to say I will come there right now but he just kept screaming at me to not dare fucking come over and to never talk to him again. I was glad to see a text from him this morning even though it read I completely ruined his birthday. I’m afraid to call the cops because I think that will just make him trust me less and probably not a good idea to have people come knocking on the door when he is so paranoid. I’m just not sure what to do. He lives with my parents but they are out of town. Even when they are home and he has had episodes like this they do nothing. And here I am feeling like I’m doing nothing?!? Anyone have experienced insight on how to deal with someone like this?