If you spilled water over the CPU (That is one of the chips inside the case), then the water most definitively was inside. I suspect you mean you spilled water over the desktop case.
Normally when this happens the first thing you want to do is to immediately remove the power from the computer. Unplug it, not just turning it off but remove the power plug from the socket. Then clean up as much moisture as you can and check the inside of the case and the hollow parts of plugs. Those will need to dry completely.
If it was clean water then leaving it near a radiator for a few days might solve it.
If it was not clean water then you would need to clean it first using clean (distilled) water and then let it dry. Esp if in the case of acids like orange juice. Anyway, you said water, so it should not be that bad.
Next you have two options:
- Remove the harddisks. Make a backup of those (these contain your data)
- Or just try it and boot it. Do not be impatient though. Wait long enough until everything is completely dry. Even if it takes a week.
In your case it sounds as if you still have moisture somewhere, conducting electricity and/or shortening things. Which means that either you did not wait long enough, or the water was polluted and left salts or corrosive stuff.
So, wait longer for it to dry. Not hours longer. Days.