I'm getting a "e<" error

SOURCE: input select button to switch between hdmi/dvi/vga

Unless there is simply some dirt or dust caught in it, I would imagine that the button has lost its 'spring' or bounce-back ability which means that either you can take the big risk of attempting to fix it or come up with some other clever way to give it bounce.

SOURCE: why does my asus monitor always read "no signal".

nah that happens with me sometimes..
have you connect the cable properly?
if that still can't make it works, first turn on your PC and monitor..
then plug off the cable that power them, so that your computer and monitor will suddenly off..
plug it on again, then your monitor will work again..
that works on mine cause my CPU is too old and had a power problem..