Facing auto shutdowns

I have iphone 7 plus. From Few weeks i m facing problem which is that my iPhone shutdown suddenly.I have changed it's battery too still i m facing problem.the battery is not even charging like it shows 1% of charge even if it's plugged in for hours.Also it is not showing battery health.Hope I'll get a solution for my problem.btw I have tried force shutdown few times,reset setting,wifi connections reset.