Ran into same problem with todays update, but could fix it (see below).
Even after sideloading it stucks in an endless boot animation with reboot loop.
It seems to be a problem when using Google apps. After sideload the image again, boot problems exists but after reflashing MindGapps to its base version the boot is successful. But some errors occur during login (e.g. Google Play, Youtube) because of the old Gapp versions.
The problem seems to be located within the Google Play Store network permissions which are all reset to zero. After allowing the network you have to clear the cache and local data for the app because of the downgrade. After that a reboot is required and you have to wait until the Google Play Store do it’s background update. Do another reboot next and update the Google apps via the Play Store. I didn’t saw any error messages after that, but haven’t time to test all apps.
EDIT: One more problem which have to be solved for people using the fingerprint sensor: Under Security->Trust agents->Reenable Smart Lock (Google)