Octagon SF8008 without HDMI, USB and RS232 output

I have an Octagon SF8008 with OpenATV image. When I turn it on after being in standby mode, it doesn't show an image on the television via HDMI, but it does show an image on a 15-inch monitor or television. I've tried several images, OpenSPA, OpenPlis, Define, etc., and they all show the same image. The television doesn't show an image, but the monitor does. I've tried to recover it via RS232, but it doesn't connect (I've tested it with PuTTY and there's no communication). The two USB ports also don't have power. Does anyone have any idea what it could be?