A method for modifying a portion of a substrate after production is described herein. The method can include diagnosing a circuit operation error causing a malfunction, identifying a first contact on the substrate, and connecting, electrically, the first contact to a second contact with at least one trace. The trace is done with a focused ion beam. The method can include diagnosing an error on an operative area of a post-manufacture circuit board causing a malfunction; introducing a metal precursor into a focused ion beam chamber; ionizing the metal precursor by contacting it with a gallium ion beam into a conductive metal and a further ion; depositing a first portion of a conductive metal onto a substrate to form a first trace; and forming the first trace between the operative area and a non-operative area thereby connecting the operative area and the non-operative area.