Baby Bird Help ASAP!!!!?

I had the same experience with one someone brought me and it did take me a while to get his mouth open, but when I did and got some formula down him he eventually learned to open up. Problem is you have to get that done soon or he won't make it. I've fed a lot of babies brought to me over the years, but never one described like yours. The closest I can come is maybe a bluejay. Good luck.