A few keys were found to be not responsing just 7 days after the expiry of the warranty. Called their service center and they said that they will charge me $300 HKD for inspection, and the cost for replacing a keyboard would be like $4xx HKD! It sounds crazy since this Eee costs me only $24xx one year ago.
Therefore, I went to ebay to buy a replacement keyboard and replace it myself. I ordered one last Friday and I got it now, and it's around $200 HKD shipped.
To remove the old keyboard, you need to loosen the clips under the battery.
After the above step, you can life up the keyboard with ease, no force required:
Remove the keyboard from its connector, put in the new one, and done!
Every keys work now!