i personally have never done this but here is a link showing what to do .
https://www.youtube.com/watch?v=IZeOrsYwJWg
it seems relatively easy from what i saw remove 10 or so screws from the bottom of the laptop, then very gently pop up the top half of the keyboard, then unplug the 2 wires connecting the keyboard part to the laptop. it doesnt show him putting in a new one but basically reverse order.
do this at your own risk i suggest you have someone who is a little experienced with you when you do this.
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edit: if the link doesnt work search this in youtube "How to replace keyboarad on Asus X550 series keyboard replacement"
i personally have never done this but here is a link showing what to do .
https://www.youtube.com/watch?v=IZeOrsYwJWg
it seems relatively easy from what i saw remove 10 or so screws from the bottom of the laptop, then very gently pop up the top half of the keyboard, then unplug the 2 wires connecting the keyboard part to the laptop. it doesnt show him putting in a new one but basically reverse order.
do this at your own risk i suggest you have someone who is a little experienced with you when you do this.