Hello, do you have anything on the screen? does the keyboard responds? I mean if you push Caps-lock, the led responds? Just a question, what kind of machine is that? I mean 386, 486..? Any other info about the hardware? When was the last time the machine worked properly? Don't be scared, PCs usually are easy to fix and cap replacement is hardly needed
This is a really hard one, with so little information. If I had to guess with little info, I would guess the PSU has died too. Does the mouse light up? (or is to old a model). Can you access the early startup routines? usually accessed by pressing the DEL key as you power it up. (on some computers this can be the F5 key - do you have the manual, by any chance?)
Do you have many cards in the computer? You may want to remove all of the cards (Very carefully!) and then try to boot it again. If it boots then, replace the cards, one at a time, and check to see if it boots after every card is replaced.
That's about all I can think of to suggest to you. Good luck.