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@@ -2,13 +2,204 @@
 
 ## Update firmware to specific version
 
-1- Download frimware version: [n24ur39w](https://download.lenovo.com/pccbbs/mobiles/n24ur39w.iso) or download from vendor
+This section explains how to convert a vendor BIOS update `.iso` into a bootable USB image using `geteltorito`, and then write that generated `.img` to a USB drive using `dd`.
 
-2- Install `[geteltorito](https://github.com/rainer042/geteltorito)`
+> **WARNING**
+>
+> The `dd` command will completely overwrite the selected USB device.
+> Always write to the whole USB disk, for example `/dev/sdb`, **not** to a partition such as `/dev/sdb1`.
+> Double-check the target device before running `dd`.
 
-3- Generate .img from .iso `geteltorito -o t480_bios_n24ur39w.img /home/lb/Downloads/n24ur40w.iso`.
+### 1- Download the vendor BIOS update ISO
 
-4- Flash iso to USB `sudo dd if=t480_bios_n24ur39w.img of=/dev/sdX bs=4M conv=fsync status=progress`
+Download the required firmware version from Lenovo or from the vendor support page.
+
+Example for ThinkPad T480:
+
+```sh
+mkdir -p ~/Downloads/firmware/t480
+cd ~/Downloads/firmware/t480
+
+wget https://download.lenovo.com/pccbbs/mobiles/n24ur39w.iso
+```
+
+If you downloaded a different version, adjust the ISO filename in the following commands.
+
+### 2- Install `geteltorito`
+
+`geteltorito` extracts the El Torito boot image from a bootable vendor ISO.
+
+#### Debian / Ubuntu / Linux Mint
+
+On Debian-based systems, `geteltorito` is provided by the `genisoimage` package:
+
+```sh
+sudo apt update
+sudo apt install genisoimage
+```
+
+Check that it is available:
+
+```sh
+command -v geteltorito
+geteltorito --help || true
+```
+
+#### Arch / Manjaro
+
+On Arch-based systems, install it from the AUR:
+
+```sh
+yay -S geteltorito
+```
+
+or:
+
+```sh
+paru -S geteltorito
+```
+
+Without an AUR helper:
+
+```sh
+cd /tmp
+git clone https://aur.archlinux.org/geteltorito.git
+cd geteltorito
+makepkg -si
+```
+
+Depending on the package, the command may be installed as `geteltorito` or `geteltorito.pl`. Check which one exists:
+
+```sh
+command -v geteltorito || command -v geteltorito.pl
+```
+
+### 3- Extract the bootable `.img` from the vendor `.iso`
+
+Go to the folder where the ISO was downloaded:
+
+```sh
+cd ~/Downloads/firmware/t480
+```
+
+If your system provides the command as `geteltorito`:
+
+```sh
+geteltorito -o t480_bios_n24ur39w.img n24ur39w.iso
+```
+
+If your system provides the command as `geteltorito.pl`:
+
+```sh
+geteltorito.pl -o t480_bios_n24ur39w.img n24ur39w.iso
+```
+
+Verify that the `.img` file was created:
+
+```sh
+ls -lh n24ur39w.iso t480_bios_n24ur39w.img
+file t480_bios_n24ur39w.img
+```
+
+### 4- Insert the USB and identify the correct device
+
+Insert the USB drive and run:
+
+```sh
+lsblk -o NAME,SIZE,MODEL,TRAN,FSTYPE,MOUNTPOINTS
+```
+
+Example output:
+
+```text
+NAME   SIZE MODEL             TRAN FSTYPE MOUNTPOINTS
+sda  476.9G Samsung SSD       sata        /
+sdb   14.6G USB Flash Disk    usb  vfat   /run/media/user/USB
+```
+
+In this example, the USB is:
+
+```text
+/dev/sdb
+```
+
+Do **not** use the internal disk. Do **not** use a partition like `/dev/sdb1`.
+
+Set a variable with the USB disk you identified:
+
+```sh
+USB=/dev/sdX
+```
+
+Example:
+
+```sh
+USB=/dev/sdb
+```
+
+### 5- Unmount all mounted USB partitions
+
+Before writing the image, unmount any mounted partitions from the USB:
+
+```sh
+lsblk "$USB"
+sudo umount "${USB}"* 2>/dev/null || true
+```
+
+### 6- Prepare / wipe the USB before flashing the image
+
+For an image generated by `geteltorito`, you do **not** need to format the USB as FAT32, exFAT or ext4.
+
+The correct preparation is to remove old filesystem signatures and partition metadata so the firmware image can be written cleanly with `dd`.
+
+Recommended:
+
+```sh
+sudo wipefs -a "$USB"
+```
+
+Optional stronger wipe of the first part of the USB:
+
+```sh
+sudo dd if=/dev/zero of="$USB" bs=1M count=16 status=progress conv=fsync
+sudo blockdev --rereadpt "$USB" || true
+```
+
+If `blockdev --rereadpt` fails because the device is busy, unplug and reinsert the USB, then set `USB=/dev/sdX` again after checking with `lsblk`.
+
+### 7- Flash the generated `.img` to the USB with `dd`
+
+Write the `.img` to the **whole USB disk**:
+
+```sh
+sudo dd if=t480_bios_n24ur39w.img of="$USB" bs=4M status=progress conv=fsync
+sync
+```
+
+Alternative using `oflag=sync`:
+
+```sh
+sudo dd if=t480_bios_n24ur39w.img of="$USB" bs=4M status=progress oflag=sync
+sync
+```
+
+### 8- Verify and eject the USB
+
+Check how the USB looks after writing:
+
+```sh
+lsblk -o NAME,SIZE,MODEL,TRAN,FSTYPE,MOUNTPOINTS "$USB"
+```
+
+Eject it safely:
+
+```sh
+sudo eject "$USB"
+```
+
+The USB should now be bootable. Insert it into the ThinkPad, boot from USB, and follow the vendor BIOS update instructions.
+
+On many ThinkPads, press `F12` during boot to open the boot menu.
 
 ## Prepare flahser
 
diff --git a/vendor/t480_bios_n24ur39w.img b/vendor/t480_bios_n24ur39w.img
new file mode 100644
index 0000000..75d6649
Binary files /dev/null and b/vendor/t480_bios_n24ur39w.img differ