HDMI not working, then reset does not work by holding power button.

So plugging in the DMI cord to tv and PS3 slim nothing however the ps3 is on and running I can hear it. I know the hdmi works because I still have a super slim and plug it in and comes up no problem. I tried to do safe mode or reboot of display by when the unit is off press and hold power obviously it beeps that time and you hold it for 30 seconds and then just turns off. So I am unable to reset it that way. I asked the guy I bought it from how he had it connected and he said with his xbox hdmi cable so if true I assume the setting should be on hdmi?