Thanks for the info. What other google accounts were on the devices? (as I understand it, there was only one child account on each device right?) My takeaway, so far, is that the ROM does not support dirty flashing (i.e. no data wipe) when only the child account is used on the device.Thanks, this didn't work. Not sure if it is because I am using a Family account on the device (kid under 13 account). Rebuild it is.
(as a side note, I hightly doubt that this has anything to do with ggow changing the ROM to support the unlocked bootloader only, but I could be wrong)