It’s most likely that you did not remove enough material from the underside of the fret button.
There should be roughly 3 mm of travel when the fret button is pushed.

The quick(ish) test:

  • Open the guitar neck
  • Remove the PC board
  • remove the offending fret buttons
  • Replace the PC board and screw down
  • Put the neck together with rubber bands
  • Put it back on the guitar body and test it