I don't see model number (more than the series please) so how about the old CMOS battery? Some PCs just stay in reset when it's too low. Is this worth a dollar to try or did you get out the Volt meter?
Have a dell inspiron that at first wouldn't do anything when I'd try to power it on. Tried the routine easy things and then decided to try a new power adapter, still nothing.
So I let it sit for a while and then decided to open it up and check all my connections. After putting it back together the light now comes on when I plug it in and it tries to turn on when I press the power button, fan starts spinning and then it just stops, still nothing from the monitor. Did notice that the memory card gets really hot when I try to turn it on, is this an indication that my motherboard is toast? If not, any ideas what else it could be?