I have a LG Stylo 2 plus I was using it it went off the only thing stayed on was the red notification light I know the battery is good because I put it in another Stylo that I have and the battery works it just fine what could be the problem
It could be on actually, if the red light is still showing. The problem is likely hardware though, so not a simple fix.
Your best options are, first if it is under warranty, contact the manufacturer. Better to have them fix it for free than to pay. If, however, it is no longer under warranty, then you should try a local tech.