Bricked Devo 10? HELP please

Hi guys,
I'm desperately looking for advice. I'm afraid I killed my brand new Devo 10.
As first step, I have installed Deviation 4.0.1 - all fine, TX powers up.
As next, I wanted to upgrade to the latest nightly. Same process, but after the DFU upgrade the tx does not switch on. No screen, no beep, nothing.
Battery voltage OK. I tried removing batteries, hoping that helps. Nope.
I cannot switch on normally, not in Upgrade or USB mode.
Is there a way to hard reset it or to force to DFU mode? Any other idea?
All help is greatly appreciated.

Thanks for the fast response. I'm afraid you are right about the hw problem. I cannot put to DFU mode either (at least not by EXT and Power On).
The only suspicious thing is that it failed right after the upgrade. Maybe only coincidence.
Right now I try to get warranty solution - it happened on day 1, not even opening (yet) the case.

Edit: Fixed.
Tried once more to put into DFU mode but this time USB cable plugged into the PC already. And I saw miracle in the form of the upgrade screen. From here putting on the 4.0.1 was easy and quick.
I'll leave the nightly install to later until I need it. (Though I do not think the nightly has much to do with my issue; probably just bad luck.)