Lumia (1520) is bricked and won't respond

I think 1 have bricked my Lumia (1520) and this happened when I tried to downgrade from Technical Preview firmware 10536 1004 to WP 8.1, using Windows Phone Recovery Tool. The downgrade was almost complete but when the phone went to the red screen with the circulating arrows, the phone just went dead. The phone just remains off with a black screen and I get no response from any of the buttons, not even the BSOD with the sad face. What can I do? Please help