Testing replacement screen and indicates charge but won't turn on

I dropped my LG Stylo 5 on the concrete and lcd was in pieces. I ordered a replacement LCD/digitizer and am now testing it before I glue everything back together. The replacement screen indicates it is charging with the circle and 30% in the middle but won't turn on when I press power button. I’ve tried the power button and both volume keys (separately and together) for 10 seconds and still nothing. What does this mean and is the lcd/digitizer bad even if it lights up that it’s charging?