Trying to get iMac G4 (17" 1,25GHz) to work, Out of ideas.

Hi all.

I am trying to get a iMac G4 to work again. The display is faulty which I have taken off ( now its only the bottom part )

It did chime before, there was activity ( hdd, fan, optical drive ) so I expected it to be only the display.

I took of the display and the arm assembly, and it chimed when I tested it after reassembly

But today when my Adapter arrived ( mini vga -> vga ) it did not chime, I can only hear the fan spinning.

1. I tried to reset the PRAM ( no results as the keyboard is probaly not recognized )
2. I tried to reset the SMC ( no luck unfortunely )
3. I tried to reset the PMU ( no luck, I also replaced the battery )
4. I replaced the thermal paste
5. I tried different RAM ( no luck )

Is the iMac a lost cause or is there maybe a way to get to boot again?

Here are the specifations of the iMac in question:

17” iMac G4, 1,25Ghz, 512MB

Greetings, Rick