This looks like a tree that was weak and then pushed to the edge by a repot when it was not at peak health. I don't know that any drastic treatments are going to help at this point. When even the old leaves whither on these guys, and the new buds fade before opening... they are likely going to either die, or completely defoliate, make you THINK they are dead and then suddenly start growing again a few months later... I have had that happen more than once with azaleas- so don't throw it away! The roots are not supporting the growth for whatever reason right now, but if there is any life left, it may well push some new roots this year and late in the summer/ early fall or next Spring it may surprise you! MAYBE...
I try to cut mine back in stages now Avoid the "SADS"= sudden azalea death syndrome. If you leave a decent amount of growth LEFT HIGH ON THE TREE when you cut back they seem to bounce back faster and more reliably in my experience.. When you cut them down to almost no or absolutely no foliage at all, SOMETIMES they just punk out and die... It has to do more with the original health of the plant and the after care than anything IMO.
Just looking at the aged signs of distress on this tree I suspect it was not in supreme health prior to the pruning and repot.
