After winning a motion to quash an unlawful detainer, what does the landlord have to do next?

If the motion you brought was to Quash SERVICE, then yes, all they have to do is to serve you properly with the original Summons and Complaint. The essence of a Motion to Quash is to say that they improperly served you with the Summons and Complaint. It doesn't quash the whole lawsuit.

A motion to quash refers to serve, not the validity of the unlawful detainer. ?If the court just ruled you were not properly served, the landlord just has to serve you properly. ?If the ruling was that there was something defective with the suit itself, then that would also have to be corrected. ?All you are really doing is buying more time, as eventually the landlord will have you evicted if there are valid grounds for doing so. ?In the meantime, you will still have to pay rent, although in some circumstances the judge might decide only a lower rent can be charged.