>>151204572 (OP)
She got tied up like that when she was meddling in things Gadget didn't want her to be involved in, for her safety. He didn't know she was there.
My headcanon is Gadget was an incredibly skilled detective, but whatever event that lead to him getting all his augmentations messed up his brain a bit. He's kind of like Robocop.
It could have been an attack by Dr. Claw that also killed Penny's parents, which is why he's protective of his neice and why he's focused on investigating MAD and capturing Claw.