My PC started smoking, is the motherboard dead?

I took everything out, used my second psu, tried to jumpstart it in an open bench, and it doesn’t turn on. Is the motherboard fried? The original PSU doesn’t smell burned, nor did it smoke. But I did forget to put in the whole 24 Pin Adapter into it the first time. It turned on for a second and shut itself off. I corrected that mistake and then it started smoking.