Good Morning
I too have my phone stuck on the 1st screen, LG Life's Good. It flashes and comes back again.
I have the sprint model and took it to the store, they said the battery is crapped out, ordered me a new one since I am within my year warranty. I am seriously thinking though it could be something to do with LG in general.
When my phone is plugged in, it works ok, as soon as I take it off, it goes into that soft brick mode. I did a hard restart 2x..
All of this started happening after there was an update Saturday morning from the sprint store app....that I did not approve.
Love it.
Best of luck, take your phone to a store and have it looked at, see if the battery will prime.