The strangest thing happened with mine.
For a while, mine was also bricked. I'd get the flashing blue light when trying to power it back on, but that was it.
After many attempts I gave up, sealed it in the recycling bag and planned on shipping it away.
I even, reluctantly, went out and got an S6 (which I hated and sold it a couple months later).
When the time came for me to post my S4, for some strange reason I figured, why not give it one more shot. So I ripped open the package, pushed the power button, and it loaded up as if nothing had happened to it at all.
THANK GOODNESS!!!!
The only thing that I can think of is that there must have been some moisture in there that had fully aired out over the months of it sitting in a draw idle.
I've had my S4 back up and running now for a few months.