Question Dissassembled laptop, put it back together. A few keyboard keys (ctrl,shift, alt) stopped working.

[Tisspaaleggen]

So as the title says something got stuck in the laptop fan, making a weird noice. Upon fixing this problem i found out that the Ctrl, LShift, RShift and Alt keys had stopped working while the rest of the keyboard seems to work fine. I then decided to disconnect - reconnect all of the keyboard ribbon cables to see if that fixed it, without success. Nothing seems to be broken as far as i can see. I also tried to connect a external keyboard to see if that worked, which it did.

I guess the question is: Seeing as theres 3 ribbon cables connected from the keyboard to the motherboard, i'd assume one would be the power supply, one would be for general keys and one would be for extra keys. Is this correct? and which ribbon would be responsible for the shift/ctrl/alt key malfunction?

 

[hang-the-9]

Most likely one of the ribbon cables are for the touchpad, mouse buttons, trackpoint, fingerprint reader or something else in the keyboard area. The keyboard keys would be in a single cable. I have never seen a keyboard that actually had different ribbon cable for different keys.