No, you didn't ruin it. :D
According to classical "compost theory" to make it perfect you need a mix of greens and browns, all you have there is greens. I make piles of just greens when I have no browns, and let them sit. They make something my soil likes, whether it's "Proper Compost!" or not.
Everything rots, just a matter of how long it takes. 3 weeks may be long
enough for just grass, probably not for kitchen scraps. I agree, dump it out, stir in anything like leaves you can, put it back in. The more you turn it, the faster it rots, and when it looks like soil, OR looks like it's not changing anymore, it's done enough.
Geoff Lawton's video is good, it does need
chickens though. If you have no
chickens, just a pile will rot nicely enough. Nature has been doing it that way for a LONG time!
What kind of bin are you using?