i have got all 3 different parts from the vaults to help the BoS but no one will accept them from me. who do i give them to? does it matter if i had the elder dismissed?

Yes, it matters. Dismissing the elder is supposed to end that quest. It was the old elder who asked you to do it.

Dude who fixes Ed-E is the one to give it to. Senior Knight Lorenzo.

I guess he won't accept it if you dismiss the Elder, which seems weird?