The Lenovo support site offers downloadable BIOS updates that can be run either from Windows or from a bootable CD.

Here's how to convert the bootable CD ISO images under Linux in order to update the BIOS from a USB stick.

Checking the BIOS version

Before upgrading your BIOS, you may want to look up which version of the BIOS you are currently running. To do this, install the dmidecode package:

apt-get install dmidecode

then run:

dmidecode

or alternatively, look at the following file:

cat /sys/devices/virtual/dmi/id/bios_version

Updating the BIOS using a USB stick

To update without using a bootable CD, install the genisoimage package:

apt-get install genisoimage

then use geteltorito to convert the ISO you got from Lenovo:

geteltorito -o bios.img gluj19us.iso

Insert a USB stick you're willing to erase entirely and then copy the image onto it (replacing sdX with the correct device name, not partition name, for the USB stick):

dd if=bios.img of=/dev/sdX

then restart and boot from the USB stick by pressing Enter, then F12 when you see the Lenovo logo.