Let her dry until she responds to drought before watering. I mean by that, let her go until she really starts to make upward trajectory with leaves just BEGGING for that light...it is the dry spells in nature that make the roots dive deeper.
Guessing what happened is, too much water drowned fresh "rootlets", coming off the taproot, and therefore, they couldn't survive, while the taproot probably STARTED to die but managed to survive this far with SOME lifeforce left. You will know when roots once more begin to grow when the plant begins to make vertical progress, the stem stops feeling "spongy", and your 'solar panels' (leaves) start really looking to take in more energy...right now, they can't DO anything with ANY amount of energy, so they are not interested in your light.