Enable developer mode
from pc phablet-config writable-image
adb shell
sudo vim.tiny /etc/system-image/channel.ini
last 2 lines change the number to be back 10 images
sudo rm /userdata/.writable_image
rm .local/share/ubuntu-push-client/level.db
sudo reboot

Wait for the announcement of a new image
drag down the indicator
click on the image notification
Setting page opens on updates but is blank