First off - he did a really STUPID thing connecting loads of speakers, he was almost guaranteed to destroy the amplifier!.
If the fuse that's failed is F902, it's in the primary of the mains transformer for the amplifiers - so there's a possibility it's killed the transformer?. There are two fuses in the secondary, F971 and F972, I would expect those to blow with a dead amplifier.
The main output transistors (fronts) are 2SC4387 and 2SA1672, you 'may' be lucky and only require those replacing, if not there are drivers in front of them, plus a large IC which feeds the drivers.
The centre channel uses 2SC4431 and 2SA1684 for outputs, and the surround is an IC, SI18752N.
Your first problem is to find which amplifier channels have been killed!. Simple ohmmeter tests on the transistors should do that!.