Samsung Galaxy s4 at&t hard brick help pls topic

I have a Samsung Galaxy s4 at&t I just upgrade it to 4.4.4 kitkat using safetra recovery method and I want to install a custom tom that y I wanna install cwm recovery from Loki but I find it difficult to install one of my told me I should unlock the boot loader that it will work then I search every forum to unlock the boot loader but I can't find and I saw the EZ UNLOCK4 APK after I install it I click unlock it says unlock successfully the I power my phone to try boot to recovery that how my phone totally dead have replace the Battery still same to power on no sign on PC pls help me pls.

Can USB JIG work on it?