Check the sticker on the bottom of the laptop
Check the label inside the battery compartment, if the battery is removable
Check the original box or packaging
Check the purchase receipt or invoice
Open System Information on Windows and look for the serial number
Open Command Prompt on Windows and run `wmic bios get serialnumber`
Open PowerShell on Windows and run `Get-CimInstance Win32_BIOS | Select-Object SerialNumber`
Check About This Mac on macOS
Open Terminal on macOS and run `system_profiler SPHardwareDataType | grep “Serial Number”`
Check BIOS or UEFI settings during startup
Check the manufacturer’s support app or website
Contact the laptop manufacturer with proof of purchase