Working on, reshaping the plug end will not hurt the mouse per se.
It is the chance that you create some electrical short that subsequently damages the mouse or host port/computer even.
Use plastic "tools" as much as possible.
A small plastic knife to wedge in and reshape bent metal. Maybe small flat end tweezers.
Remember there may already be some problem within the plug itself - damage you cannor see or repair.
Overall a small risk I think but you do need to be aware of that risk.