Nighthawk MR5200 power off

I have a Nighthawk MR5200  mobile hotspot installed in my home office.  Seems to be working well.

Since it is "permanently" installed, I removed the battery per manual's suggestion.

What is the proper shutoff procedure?

• Turn off external power?
• Hold button till red "Shutdown" icon appears, then press icon?

I ask because of the possibility that there is some sort of "write to file" procedure

that the device wants to do during shutdown.

But this procedure might just be there for shutting down when a battery is installed

and cutting external power wouldn't actually turn it off...