Killed just under 1k access points when they all upgraded on one go. They had no problem erasing the firmware but when they all tried to download the new one at

Killed just under 1k access points when they all upgraded on one go. They had no problem erasing the firmware but when they all tried to download the new one at once it killer the service and we ended up with a lot of blank APs. The conformation message for 1 or 1000 APs is unhelpfully "This will overwrite all existing system images. Are you sure Y/N"