Progress!
You should check for firmware updates from Lenovo. If the problem continues,
we will need data to understand the shutdown failure. You may find it useful to keep a list of boots with a note for the time you did a shutdown and success or failure. This will make it easier to find the relevant records using journalctl and compare successful and failed shutdowns.
Shutdown failures are often due to some network process refusing to die. One easy test for that is to try disconnecting from the network before shutting down.
