A user is unable to start a computer following a failed Windows 10 update.

Booting in safe mode is the initial step to diagnose a computer experiencing a blue screen of death (BSOD) following a failed Windows 10 update. Safe mode starts the computer with a minimal set of drivers and services, allowing troubleshooting and identification of the problematic software or driver causing the BSOD. This mode provides a safer environment to uninstall recent updates or drivers, perform system scans, and restore the system if necessary. Other options like System Restore wizard, last known-good configuration, and resetting BIOS settings may be subsequent steps but do not directly diagnose the issue as effectively as booting in safe mode.