1. you possibly installed the transistors wrong.
2. there are several other components such as diodes and resistors on the board which are defective.
3. if it blows a fuse, there is a dead short.
4. sounds like this unit should have been repaired by an experienced technician, using proper test equipment.
A schematic only does you good if you have the experience and tools to use it. An inexperienced person will gain nothing from a schematic.