A microwave in a motel room, we arrived and did not use for a couple of days. Then we nistakenly used, we believed that, being clean, being not used for 24+ hours, it was ok. Now we read we should have put water in a cup for 20 minutes on max setting. Should we do that now? And the water container becomes treif? (Maybe use a disposable cup?) Thanks so very much for the list, the forum, and everything you do. Chag Sameach.
If the microwave is clean, you don’t need to kasher it.