Default Mygica help me unbrick bricked atv1200

I tried to make the internal memory swap adb method found on the forum, but the command adb devices stuck. I tried to restart and nothing, I removed the power cord and still not finished, I removed the USB cable and so died. I put the power cord back but never lit, illuminates only when connecting the USB cable, I managed to get into recovery mode, I managed to install firmware restarted and the screen remained black. the idea is that it is powered only by the USB port, which led me to do? has anyone happened to that? Thank you!