What happen if I throw water on my computer while it's open???

the water will ruin your computer. you should already know that...

It will confirm the stupidity of your actions

External damage doesn't mean that your laptop won't run, and not running isn't necessarily a symptom that the laptop is broken forever. If your processor or motherboard gets damaged, you're better off getting a new laptop, but you can usually replace a damaged hard drive or RAM, fill in cracks in the case, replace the keyboard and even install a new screen.