I was in a similar situation some 50 days ago - and now my poor Phal has no roots at all
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In my experience, water + damaged roots = root rot, almost certainly. And when repotting, there's bound to be some root damage, but it's almost impossible to tell where and to what extent. My conclusion for the future is as follows:
I would soak the roots for 30 minutes before repotting. This way, the roots will get as much water as they need, they will become more flexible, and the plant will be able to resist without watering for 2-3 weeks.
Then I would dry the roots surface, using an absorbant paper towel.
Then I would cut rotted and dried roots and sprinkle cinnamon on the cut surface (but not on healthy roots!).
Then I would repot in almost-dry medium (not moist!) and refrain from watering for 2-3 weeks. Roots need 2-3 weeks for healing any damage.
I would mist the medium surface every day (only before noon!) during those 2-3 weeks, just to provide some humidity, but I would not water. This would also stimulate the plant to grow some new/branching roots, looking for water.
I hope that experience growers will chime in and confirm (or not) the above.