Have you tried all of the hdmi plugins, gpu and the onboard cpu graphics hdmi? You could also try the displayport if possible. If none of that is working, you could wipe the CMOS and then plug into the onboard HDMI. I have gone through this myself and just last night as a matter of fact. I changed my gpu and had a black screen, so I put the old gpu back in, still black screen. I then pulled the gpu altogether, reset the CMOS, after watching a video I found by searching, "CMOS reset Asus G20". There is a guy on this forum that has made a lot of G20 videos name Welsh Gamer and I owe him a huge thank you for his videos. So if all else fails look the CMOS reset video up, you will have to look up the other video on how to get it apart first. After the CMOS is reset, plug into the onboard HDMI and you should get that Ameritrends screen you talked about earlier, you hit enter to reset the bios defaults, and your off to boot. Once I got mine going, I shut it down and put the new gpu back in. It took a couple minutes after I started the computer for it to recognize the video card, I had already loaded a driver that worked with it. Once the computer posts a message saying it has recognized the gpu, you can shut down and plug into the gpu's HDMI, if that does not happen, go to the gpu vendors website and download a driver for it. Best of luck.