What changes do you need to make? If it's a boot order setting, you may not need to. [br]
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If the device has no OS, connect or insert your installation media (USB drive, disk, etc..). In theory, when you turn the device on, it scans through the list of boot options in order of priority, until it finds a viable one in the list. If the install media type is higher in the boot priority list than any other "viable" OS, the laptop should automatically boot to it.
Complications may arise if that's not the case. [br]