The ASUS S400CA series can only flash the BIOS back to the version that came with the system before leaving the factory (it depends on the version that comes with the system, which is usually earlier).

Applicable situations:

　1. No display after power on.

2. The last BIOS flash failed and first aid is needed.

Required tools:

The laptop contains a recovery hidden partition of the factory-installed system.

Notes:

1.) There are certain risks in flashing the BIOS. Please be sure to back up important data in the computer hard drive in advance;

2.) During the BIOS flashing process, be sure to connect the power adapter and ensure that the battery has at least 30% power to prevent power outage midway, and avoid pressing the keyboard, mouse, or plugging and unplugging USB devices.

3.) Taking UX21E as an example, the default BIOS version is 205. The screen and file names seen during operation may be slightly different, depending on the actual model.

Step 1: With the laptop turned off, press and hold the [Ctrl] and [Home] keys on the keyboard at the same time, and then press the [Power] key to turn it on.

(For some models where the [Home] key is not an independent key, but is combined with a function key and cannot function alone, you need to press [Ctrl] + [Fn] + [Home] at the same time. button)

Step 2: A blue screen will appear on the display. At this time, the computer will automatically start the process of flashing the BIOS. Please wait for 1 to 5 minutes when the computer completes the update to 100%. , will automatically shut down.

Step 3: Wait for the computer to shut down automatically, turn it on again, and press F2 when the ASUS LOGO appears to confirm whether the BIOS version has been changed. In the picture below, the BIOS version has been flashed back from the original default 205 to 204.