Any car mechanics here? Altima ebrakes not working after changing rotors

Today I changed my rear wheel studs, rotors, and brake pads on a 2005 Nissan Altima 3.5SE

I've looked up the issue and found many people saying after they replaced the rear rotors the ebrake doesn't function properly. Most of them were resolved with a simple adjustment. I've tried these with zero results and I don't believe they have the same issue that I do.

There is ZERO resistance pulling up my ebrake lever all the way. An infant could pull it up until it hits the plastic.

One the second side, when I was replacing the wheel studs (a bunch of my wheel studs were stripped, I'm guessing from mechanics using impact wrenches), a clip and tiny little cylindrical piece fell out the bottom of the (brake shoes? -- I'm not even sure what this part is...behind the rotor there is a small revolving piece that holds the wheel studs and behind that is this spring loaded contraption that is the parking brake)...



It fell out of that..I put it back in but I'm guessing it was holding a cable in place? I'm guessing that cable has retreated? I can no longer see a cable leading to that little lever thing.

Is there something more I can do or do I need to bring it to someone who knows what the frick they're doing?

FYI the regular brakes are working fine.