It depend if the Neutral was installed.
If there is no Neutral, may be just replace the Powerwall with a connection box to protect the wires.
To have a legal NEMA 14 50 require adding a Neutral, and may be a new 50 A circuit breaker.
Adding a new wire in a conduit is not easy, unless it is very short with not too many curves.
So it would be simpler to put connection box and put back a new Powerwall when needed.