This document provides service instructions for notebook computer models W255BU, W258BUQ-C, W258BUQ, W252BUM, W255BU, W251BUQ, W251BUQC, W258BWQ, W258BWQ-C, W251BWQ-C, W251BWQ, and W255BW. It contains safety and handling instructions, disassembly instructions, part lists, schematic diagrams, and instructions for updating the BIOS firmware. The document is intended for use by service personnel to maintain and repair these notebook computer models.