Reconnect a sender whose LinkedIn session broke. `status` is `reconnected`, `checkpoint_required` or `failed`. In every case the sender keeps its id, its campaigns and its seat. For a credentials / infinite-login sender this retries the saved sign-in and runs one attempt now. If its saved provider account no longer exists, a replacement is created from the stored credentials and attached to the same sender. If the person changed their password (or 2FA), pass a new `password` (and `totpSecret`) to replace the stored credentials first. Any credential field (`totpSecret`, `username`, `country`, `proxy`) needs `password` alongside it (400 otherwise). An omitted `totpSecret` or `proxy` keeps the stored one, but `country` is replaced, so send it again if the sender has one. Seats are not checked here: a sender reconnected beyond the plan's seats is parked again within minutes. For a `cookie` sender, omit `liAt` to sign in again with its saved browser session, or pass a fresh `liAt` (and ideally the `userAgent` it came from) to replace it. A `liAt` from a different LinkedIn account, or one LinkedIn asks to verify, is refused with status `failed`. A legacy sender with no stored credentials at all can be repaired by passing `username` + `password`, which converts it into a credentials / infinite-login sender from then on. The alternative for any sender is a hosted connect link scoped to it (POST /accounts/hosted-link with `accountId`), which lets the person sign in themselves. A stored authenticator secret clears a 2FA challenge on its own. Any other challenge comes back as `checkpoint_required` with the `checkpoint` to answer on POST /accounts/{id}/checkpoint.