Check the label on the bottom of the laptop
Check under the battery if the battery is removable
Open the BIOS or UEFI settings
Use the Command Prompt and run `wmic bios get serialnumber`
Use PowerShell and run `Get-CimInstance Win32_BIOS | Select-Object SerialNumber`
Check the system information page in Windows
Look in the laptop manufacturer’s support app
Check the original box or purchase receipt
Check the warranty or registration documents
Contact the manufacturer’s support with the device details