LG document labelled MS-0746, filed as a schematic in a 2.00 MB PDF. The name gives only the brand and the MS-0746 code and no product type, so check the cover page to see which unit or module it covers. Service schematics of this kind are used to trace supply rails, follow control and signal lines, and identify components by reference designator during fault finding. Any PDF reader opens it. Confirm that the code printed on your board or service label matches MS-0746 before working from the diagrams.
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 @datasheets1. 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.