Compaq Deskpro (probably Mainboard failure)

Hi there!

I just got a pretty old Compaq Deskpro config, really nothing special,
approxx 1,3 GHz, 128 RAM, everything else integrated, and with a small
HDD.

the box wasn'tg opened, so the computer was untouched for like five
years.

i tried to turn it on, but nothing happened...
the led on the mainbord is on, so the power supply is OK (I tried
another one too...)

the cables leading to the turn on button seem to be OK too, cuz i
tried to connect the jumpers manually, and still nothing happened.

i don't know what the problem is, the PC is too old for a complaint;
and I really dont know what know.

i mean can i fix it somehow? probably not, but i'm courious, maybe i
didn't try everything...