In the end it comes down to time and money.

Not all Macs can be fixed, even with the appropriate knowledge and test tools.

If you are not prepared to wave a soldering iron then there are very few real fixes you can do on compact macs other than unplugging and replugging components.

There is plenty of information on this website, including references to a very good pdf that describes fixing classics, but not for the feint of heart.

http://68kmla.org/files/classicmac2.pdf