Trouble Unlocking Verizon LG G5 VS987

A recent "security" update left my Verizon LG G5 VS987 in an unworkable state. It no longer knows its IMEI number and thus cannot recognize the SIM card. I've recovered the IMEI from the inside back cover but can't figure out how to restore it. LG wants $40+ to fix it, which I'm not inclined to...

Trouble Unlocking Verizon LG G5 VS987