Just saw this. Was answered in other post.

Its dead. The main shoot died from too wet,too dry, too chilled for too long as a seed, or even too much peat in the potting mix you used. Your best bet is to plant MANY Mango seeds- all you ate of a box of them,and you will quickly learn that vigor is wildly varied seedling to seedling. Keep the best,cull the rest.

It's amazing to me that it's still not obvious to people that they need to give some indication of where in the world they are...

I'm seeing something in photo 3 that looks like it might be an infestation. I'd suggest cutting it off and taking it to your local Ag Agent. Your leaves look like they are not getting water. How was this planted? Did you dig a hole and then added bagged soil? You shouldn't do this because there might not be a lot of water transfer between soil types. Always use the soil you took out of the hole. Our adobe-type soil really is pretty good if you keep it watered. Was it root-bound when you planted it and didn't get unwound? Perhaps the roots have spread out and you're watering only by the base of the tree. There are a number of reasons for lack of water. Like was said above, check various areas after watering to see if the roots are getting water. Also, you might be fertilizing too much. The Ag advice is 3 times: February, March/April and then in July. I'm not sure why the Epsom Salts. I just use Citrus fertilizer those three times, and my lime, lemon and kumquat are fine. ( They are in the ground, not in pots. Pots need more frequent fertilizer.) Good luck! Kate