D-Pad no longer working

hi all!! i just re-shelled my old gba sp, but the d-pad no longer works on it. i tried taking it apart again to see if any debris blocked the contact from working, but after clearing it, nothing changed. i used IPA to scrub everything clean before putting it all back together the first time and had heard that it could get in the button contacts while researching my issue. is that a safe bet? how could i fix that??