Lenovo IdeaPad U350 repair archive, a compact RAR of 583 KB. The name gives only the model, without board number, revision or description of contents, so unpack it with WinRAR or 7-Zip to see what it contains. A file of this size most often holds a schematic in PDF form, useful for tracing power rails, checking the charging path and finding which component pulls a line to ground. Before measuring, read the board code on the U350 PCB and confirm it matches the document, because a model can have several board versions.
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 @IT_SERVICE_WORLD. Enginerys does not host this file.
How to open a .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.