Have you just had the update to Android 11 installed? It just came out and was installed on my device on Monday. After that, the device crashed after a short time every time I restarted it. And it did so while the "Finishing Updates" notification was still displayed.
What helped me: Reboot once without SIM(s) and without external MicroSD (if you have one inside). On the next start, the "Finishing Update" ran through and then I could switch off again, insert SIMs and card and on the next start everything ran as before!
Even if they didn't have an update or the notification: a restart without SIMs and MicroSD might be worth a try.

It was the same for us, but unfortunately it's been spinning again for 2 days. Version Android 11 is already on it, but if this fuss starts with every update...