How to update the BIOS on a Lenovo T400 laptop

This blog post explains how to update the BIOS to version 3.24 (released on 2012-12-16, latest release as of 2018-04-21) on a Lenovo T400 laptop.

This instructions below don't seem to work, I get an Operating system not found error when booting from the pen drive. Unfortunately I don't know how to fix that.

You will need a working and charged battery pack for the BIOS update, so install the battery pack first and start charging it.

If you are running Windows XP, Windows Vista or Windows 7 on the laptop, download the BIOS Update Utility from here (choose 32-bit or the 64-bit version depending on your Windows type, or try both versions if you don't know), and run it, and you are done.

Otherwise, if you are able to burn a CD or DVD (either on the Lenovo T400 laptop or on another computer), and you have a working DVD reader in the Lenovo T400, then download the installer DVD .iso from here, burn it to a DVD, insert the DVD to the Lenovo T400, reboot the Lenovo T400, press the blue ThinkVantage button (near the top left corner of the keyboard), press F12 to select a boot device, select the DVD, boot from it.

Otherwise, if you have a USB pen drive of at least 34 MB in size whose contents can be overwritten, and you have a Linux system running (either on the Lenovo T400 laptop or on another computer), then connect the pen drive, figure out the device name using sudo fdisk -l (typically it will be /dev/sdb or /dev/sdc, but be extra careful, otherwise you will overwrite the contents of some other drive), run this command to download: wget https://download.lenovo.com/ibmdl/pub/pc/pccbbs/mobiles/7uuj49uc.iso; run this command to copy the bootable BIOS update utility to the pen drive: sudo dd if=7uuj49uc.iso of=/dev/sdB bs=49152 skip=1; sync (replacing /dev/sdB with the device of the pen drive). Insert the pen drive to one of the USB slots of the Lenovo T400, reboot the Lenovo T400, press the blue ThinkVantage button (near the top left corner of the keyboard), press F12 to select a boot device, select USB HDD, boot from it.

After booting into the BIOS update utility, follow the instructions to update the system software. (Don't reboot or turn off until asked.) The next reboot will take longer, the Lenovo logo will appear and disappear 3 times. After that you are done.

Now if you enter the BIOS setup at boot time (by pressing the blue ThinkVantage button), you will see version 3.24 (7UET94WW) 2012-10-17.