Edison Format · March 2010
It will not regain it even if "Power Pickaxe" stops being negated.
This effect targets the monster in your opponent's GY.
Removing the monster is an effect, not a cost.
If the target monster is not removed from play by this effect, the equipped monster does not gain ATK.
If the Level of the equipped monster is lower than the targeted monster when this effect resolves, the targeted monster is not removed from play.
Removing the target monster from play and gaining 500 ATK happen at the same time.
If "Power Pickaxe" is negated, the equipped monster loses the 500 ATK. It will not regain it even if "Power Pickaxe" stops being negated.
Source: j-wiki.)
If "Power Pickaxe" is destroyed, the previously equipped monster loses the 500 ATK.
Monsters removed by this effect remain removed from play even after the End Phase.