1. Visit http://support.asus.com/download/download.aspx?SLanguage=en-us, search 1001HA and choose DOS as operating system. Download latest bios rom file.
2. Save and extract the downloaded file. You will get a rom file named like "1301.rom"
3. Format a usb pen drive to FAT-16 partition. In my case I used a 32 MB SD card which came with my old Kodak camera, and I used a SD card reader that PC can see it as a usb disk. Copy 1301.rom to its root folder and rename it to 1005HA.ROM. The reason for renaming it to 1005HA.ROM is that EZ Flash on this 1001HA netbook looks up rom with this name. If EZ flash failed saying trying to find a rom file with another name, just shutdown the netbook and rename your rom file to the required name and try again.
4. Plug in the usb pen drive and reboot the netbook. Make sure that during the ASUS splash screen, press ALT+F2. Then EZ Flash will run automatically and try to locate the usb drive and read from file 1005HA.ROM (in my case).
5. It takes around one minute for me to upgrade everything. DO NOT TURN OFF OR EVEN TOUCH YOUR NETBOOK DURING UPGRADE. Read the messages on the screen and when it says you can press the shutdown button, you can turn off your system.
6. Turn on your netbook again and enter BIOS to check if the BIOS version is up to date.