It depends. If its modular enough then you can get by with just limited knowledge and enough skill not to stab yourself in the hand with the screwdriver.

Tony has a fairly good idea of what is wrong and how to fix it just from reading other accounts. The problem is that the spare part is just way too expensive to order to just give it a go. If you mean getting to the level where you're actually replacing components on the board then thats pretty much gone unless its a simple or easy to diagnose fault.

Most repair places just throw out the entire module/board and get a new one now since its just not worth spending hours/days poking at a board with schematics that consist of some massive black box ICs and a handful of components. The basic checks would be to see that everything is getting power. Any analog stages are working. The big ICs are getting some kind of input. If that all passes then chances are that something has died within the big ICs.