It looks like you went a bit too far in taking things apart!
These are the battery contacts which are welded to the bus bars leading to the micro controller board and then onward to the system via the power feed.
I would carefully re-assemble the battery putting the insulator pads so things don’t short out if the battery is still good. Otherwise time to dispose of it properly at a battery recycle center with the insularity’s back on as you don’t want to cause an electrical fire.