Посмотрите, может с la-291p расположение серийников совпадает viewtopic.php?f=394&t=112024&p=665904&hilit=b291p#p765143
Но они прописаны в основной флешке, а не в мульте.

На офф сайте, в апдейте для вашей модели, есть утилита для прописки идентификаторов wflash2.exe.

...скачал утилиту, только не пойму как пользоваться ей...

The default operation of the flash update program is to use the graphical user interface provided by the AFUWINGUI program. You can also run the program from a DOS command box (with Administrator privilege) by running "flash.cmd". Before running the "flash.cmd", please change the command line to the options you need. The command is:

wflash2.exe [option1] [option2] ... [optionX]

[OPTIONS]
/h Show help messages.
/rsmb Preserve all SMBIOS structures.
/ncb Program all non-critical blocks.
/clr Clear BIOS settings.
/ign Ignore BIOS version check.
/sn:nnnnnnn Update system serial number (up to 20 characters).
/csn:nnnnnnn Update chassis serial number (up to 20 characters).
/mtm:nnnnnnn Update machine type and model number (up to 20 characters).
/tag:nnnnnnn Update system asset tag (up to 25 characters).
/uuid The flash utility will generate an Universally Unique Identifier (UUID), replacing the one that is currently in the system.
/logo <filename> Change logo. The size of logo file after compression should be less than 8KB (the size of compressed logo file is displayed on the screen during the processing).
/cpu Update CPU microcode.
/reboot Automatic reboot after all requests done.
/pass:nnnnnnn Input current system password.

The following example shows how to update system asset tag number to "1234567" use command line:
flash2.exe /tag:1234567
The following example shows how to update BIOS and update system asset tag number by one command:
flash2.exe bios.rom /tag:1234567
The following example shows how to change the power-on logo.
flash2.exe /logo:myfav.bmp

Note: A flash update image using these program options should be tested carefully before widespread usage.