S9+ unlocked, but cannot access network with Verizon SIM installed

[Brannok812]

Unlocked phone purchased in Shenzhen, China. NO SERVICE message with new or current Verizon SIM card. Recognizes Verizon SIM and tel number. Preferred Network Type: tried selecting Global (that is the selection on my currently functioning LG G6), but selection does not seem to be saved. Each time I open this menu, all radio buttons are unchecked. Tapping or long pressing a selection takes it back one menu step. Preferred Networks menu shows many 2G and 3G options, but nothing familiar. Location is "ON", but still thinks the phone is in Chinese time zone. How to enable the phone to recognize the local 4G network? I have tried using my own SIM (Verizon) and a new SIM (Verizon, new phone number for my daughter). Phone functioned when I put my SIM in it while in China.
BTW, now the side buttons have stopped working.

 

[Rukbat]

It worked with a GSM SIM but it doesn't work with a CDMA SIM. It's possible that, since there's no CDMA service in China, the phone can't be switched to a CDMA carrier. Just a guess. (I'd bring it into a Verizon corporate store and ask them for assistance.)

[Moved to the S9 & S9+ forum, so more S9+ users will see it.]

 

[rizzo269]

Is it possible the phone sold in China doesn't have the LTE bands needed for Verizon in the US?

Or maybe the Verizon firmware needs to be flashed? I don't have much experience with unlocked devices so I'm just throwing some ideas out.

 

[Brannok812]

Thanks for the reply. I tried once at the Verizon store (see below). I will try again.