My RPi2 keeps both ACT and PWR leds on

[Vitorbnc]

Hi,
I have a Raspberry Pi 2 and was powering it using the GPIO +5V and GND, it was working fine. However, I tried powering it using the USB port instead, there was smoke and it stopped working.
Then I replaced D5, which was getting hot and now both green(ACT) and red(PWR) just keep on. I also touched the board near D5 and noticed U16 is getting hot.
Is it dead?

[Rive]

Sounds like you killed it.

[Vitorbnc]

Isn't there any component I could replace to make it work?

[Rive]

Isn't there any component I could replace to make it work?

Doubtful. Since you let the magic smoke out.

It is possible you just blew the fuse.

Using pin 2/6 or 4/6 for 5V Ground to power, is similar to what people do when they connect a battery pack for powering the pi.

Let me get this straight, you put external voltage to the pi's regular USB hub, right? Why would you do that? Why not just use the mico USB port which is the power port?

If you did connect to the micro USB, what was the voltage power supply of the USB you connected? Was is more than 5.25V?