The machine won't boot but the lights come on, and the fans spin? That doesn't sound like the CPU to me..................with an old machine I still go for a dead CMOS battery.
If you have a multimeter/battery tester or know someone who does then check it out.
Better still, remove the battery and take it to the shop where you would buy a replacement and ask them to test it for you to see if you need to buy a new battery from them
If you cannot do someone any good: don't do them any harm....
As long as you did this to one of these, the least of my little ones............you did it unto Me.
What profiteth a man if he gains the entire World at the expense of his immortal soul?