Sony MBX-202 mainboard schematic, tagged M790, which appears to be the ODM project code for this design. Provided as a 779 KB PDF with no revision or laptop model stated. A technician can use it to follow the power path from the DC input, check standby and main regulators, locate test points and track down a component pulling a rail to ground. Compare the MBX-202 label on the PCB and note any revision mark before relying on values; a similar copy exists.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @schematicslaptop. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.
Any PDF readerSumatraPDFFirefox / ChromeFlexBV (links PDF to boardview)