Answer to: Why doesn't my Asus T300 Chi trackpad work?one of two things probably, one windows 10 auto disables your trackpad in some instances when a plug in mouse is available (or it thinks one is available) or two, your drivers are messed up you need to get the right one off of your computer manufacturers website, uninstall current ones (ones that windows 10 put on your machine instead of the ones that were working) then install the correct ones that you obtained from their website.
Answer to: I want to repair my asusShort answer, Yes...most of these things are fixable... For the cost of a complete mobo though...you might not want to replace it due to you looking at 50-60 dollars in the main board alone, that's not including any secondary boards. However, more information on what is wrong might help narrow down what boards with which problems you are experiencing. Being that this laptop is 3 years old and was an ultrabook it's quickly approaching EOL as well, which should be taken into consideration. Regards, A Tea Drinker