Sorry to hear about the losses but IME seedlings don't turn "crispy" by just forgetting to water one day. They may wilt, sure, but then perk back up once watered assuming that it hasn't been many days without watering.

The crispy leaves would indicate to me that something else was seriously wrong. Crispy leaves usually indicates to me over heating in some form - excess sun exposure, high ambient air temps. excess heat from supplemental lights, etc. combined with not enough water and very dry air.

In other words the moisture in the leaves has to evaporate for them to turn crispy. That can happen very quickly with root bound plants that have little to no air circulation. Any possibility of other factors?

Dave

They seemed to be rootbound, could have more airfllow.and they werepretty close to the lights