Call Lionel and see if they will replace the remote under warranty, as this is a new set.
The remotes are not cataloged separately, as they are matched to a specific locomotive type, and have to be ordered directly from Lionel.

Give Lionel service a call, tell them you have a dead remote, and give them your set number 6-30183 and locomotive type 2-4-2 to get the proper remote.

Larry