Phone not responsive after power losing while upgradeing

Did you do a software update through the phone settings or did you do it via the computer?

Also how much battery was left on the phone before you started the update?

Also can you try holding power + volume down + home for 15 seconds and try turning the phone on? Hopefully it isn't hard bricked.

If you can get the phone into download mode, in a soft-bricked state it requires holding power + volume down + home button down for a fairly long time until you see the light blue odin download mode prompt screen then you can boot download mode.

Details on how to flash firmware as shown in this guide link:

http://updato.com/how-to/how-to-install-...

Note that the firmware you will download will contain multiple files in a compressed file that needs to be extracted which will be the following which will need to be flashed using ODIN following that guide:

Make sure model number matches phone, you are downloading latest samsung firmware for your phone 7.0 for example and the CSC country code matches your phone (For example XSA not really required since your phone is in a bricked state and can't really get CSC code unless you boot recovery mode)

BL (Bootloader)

AP (System partition with recovery + system software / firmware)

CP (Modem)

CSC (Use Home_CSC if you want to keep user data on your device which is probably what you want)