At early stage of growth and development fruits generally drops from plant due to moisture stress and competition between fruit for carbon partitioning. You can manage this fruit drop by maintaining sufficient moisture and fruit thinning. But in your case it seem that the trees are still in juvenile phase. In contrast to many other fruit crops pomegranate trees set fruit on at a young age. However, the tree is not developed enough to support fruit load. As a result with the advancement of fruit growth they eventually drop. In pomegranate fruit drop is common in the first 2-4 years. Try to avoid crop in first 3 years to encourage vegetative growth Hammad Hussain

Read the following guidelines about pre mature fruit drop in pomegranate and how they can be controlled?

https://homeguides.sfgate.com/pomegranate-tree-hold-fruit-60108.html

I think the browning may be due to "heart rot" in pomegranates. Read the following review article i guess it may give you the idea.

https://doi.org/10.1016/j.scienta.2016.08.016