Motherboard repair schematics are not readily available to end users. The only way you could even POSSIBLY get that would be directly from a Biostar technician, or from the company itself, and both of those are extremely unlikely as it's just not something that is typically made available to the general public OR even to professional electronics repair shops.
To be honest, even motherboard manufacturers don't very often repair faulty boards. They simply replace them with RMA stock because it costs less money and generally doesn't result in a warrantied board coming back a second time due to a poor repair. Generally, they just throw boards that have something wrong with them into the scrap bin.