Originally Posted by Lifeshield;14446347 E66 means the console is banned from Xbox Live.
Regardless of your reasons for updating firmware or flashing the system it will get your system banned from Xbox Live as it is against Xbox Live TOS to modify your system in any way.
In an effort to help you troubleshoot any problems you may have with your Xbox One at launch, Microsoft has compiled a list of error codes you may encounter after updating your console software.
Similar to the Play Station 4, these error codes are a random string of numbers and letters that don't mean much to the average consumer.
Exclude the first 2 characters (Ox),l the next 8 characters will point to you to the error codes listed below.
If you have an Exxx xxxxxxxx xxxxxxxx number displayed across the bottom of your screen after a system update you will not need the step above, locate your Exxx error message from the list below This error means that your Xbox One requires a system update, but the update is not currently available.
Note: The “x” digits vary according to several factors, such as region or country.However, website 360Mods says different, providing a fix to get those custom consoles back on Live.The new workaround, i Xtreme LT (Light Touch), tries to make the altered firmware appear as the original, Microsoft-certified version while keeping the modded information.E65: DVD Drive Error - Most often caused by a DVD tray/drawer that did not fully close.E66: DVD Drive Error - DVD model, version or software do not match.Originally Posted by Hardheaded Murphy;14435876 even if the device is flashed back to stock firmware, the ban on device will stand, and will more than likely remain on microsoft's device blacklist. I updated the system before (not knowing it was flashed). My Xbox live membership is fine I can sign in, then there is an update.