Press the power button a very long time... Til phone vibrates.

And are you sure its charged?

---------- Post added at 10:49 PM ---------- Previous post was at 10:47 PM ----------

And did you unlock the bootloader? If its not a dev edition, unlocking bootloader voids warranty.

---------- Post added at 10:49 PM ---------- Previous post was at 10:49 PM ----------

As does flashing other carriers firmware I suspect.

But, maybe you'll get lucky!

Good luck!
Sent from my N5, N7, Moto X, GTab3 or S2.

Need help with poor battery life on the N5...or any device really? Lots of info in first 4 posts! >>>>
[Battery Life Help] Troubleshoot Battery Issues Here....and Tips