Don't use any other tool than the German made DF-17, German steel Weld breaker to separate freshly drilled panels. Use when spot welds are not completely detached because of sealant, bonding glue or drill through debris.
This specialty tool will cut through to free the panel easily and cleanly without causing more damage. Simply tap with a hammer to insert and then tap on the side to cut through and free the panel. The weld breaker is sharpened on both the leading and side edge. Easy to re-sharpen when dulled.