If when you login you choose advanced options for Zorin startup, and then choose an option for a previous kernel and that should work. Once you're in and running you can then uninstall the more recent kernel or otherwise work on resolving the pwd issue .
I highly recommend using the TuxInvader Kernel on Zorin OS 16 if you need to elevate beyond the Zorin OS Supplied kernel.
It is solid, true and just works. The below command will install the 6.3 kernel: