Power On No Display Or Chime

I have recently acquired an older style iMac, 2009 - 2011 ( I am unsure on the year it has 8GB of RAM, a 1 TB HDD, 2 3.5mm jacks one for mic and one for headphones, 4 USB A Ports, a Fire Wire, Ethernet, and a single Thunderbolt port if that can help narrow it down), that when the power button is pressed the fans come on and the HDD spins but nothing on the display, internal or external, nor does the startup chime play. I have opened it up ensured everything was connected and changed the button cell battery. Any leads on what I could replace to get it going would be appreciated.