Ay, depende talaga sa condition niya! If it's just a small bruise or scratch, okay lang kainin, pero make sure you cut off the part na medyo nasama or nag-darken na, kasi doon pwedeng mag-start ang bacteria or fungi. One of my mum friends always does this sa fallen mangga from their tree, she just cleans it well at cuts the damaged parts, tapos okay na.
Pero if the mango is mushy na, madilim na malaki, or may weird smell, better skip it na lang para safe, lalo na kung para sa kids, hindi worth the risk of upset tummy! Fresh is always best, pero walang sayang with mangga ha, you'd be surprised kung gaano karami pa rin ang kain-able part.