A lot of things happened during the time Jin decided to train while Eve worked on his original body. He needed to become as strong as he needed to be in order to defeat her, while she needed to get his body up and operational so she could accomplish her goals.
In order for everything to be operational within the six months timelimit, Eve worked hard every single day, not leaving the lab, and operated on Jin's old body.
"Madam, the laser scalpel can't pierce his skin. It's as if it were made out of an unbreakable material." Yuno's laser scalpel ran out of energy before it was able to pierce Jin's old body.
"We'll come back to that later. For now, we will upload the data we collected from Jin into his brain."
"Understood."
