To be honest this is a bit a shot in the dark as your issue could be caused by many reasons. But one possibility is that your SD card has an incompatibility problem with the sdhost driver that has been activated with the latest update as discussed e.g. here Not booting after December update - #50 by Mandragore
As mentioned not 100% sure if that is the reason and also which exact status your system is in but maybe you try to download the mmc overlay and at dtoverlay=mmc to /boot/config.txt as discussed in that thread