As long as the battery pack is still sealed and the interlock systems are undamaged and working correctly, it's no big deal. You follow the manufacturer's instructions to make it safe, then work on it like there's no voltage present.
If the battery pack is broken or a prototype or whatever, yeah, then you need to think things through carefully before doing them. And have a plan for what you're going to do when things go wrong.
Source: I work in electric aviation and work on battery packs.
As long as the battery pack is still sealed and the interlock systems are undamaged and working correctly, it's no big deal. You follow the manufacturer's instructions to make it safe, then work on it like there's no voltage present.
If the battery pack is broken or a prototype or whatever, yeah, then you need to think things through carefully before doing them. And have a plan for what you're going to do when things go wrong.
Source: I work in electric aviation and work on battery packs.