many times folks with no image on mini retina are trying a mini original lcd, and not a mini retina lcd. this won't work even though the connectors are the same.
unlike many parts, it is rare for a replacement lcd to just not work out of the box. so if that is the case, then this will be a simple backlight fuse job.
for mini retina, you'll need to send it out for backlight repair---unless you are a capable microsolderer.
if you need some microsoldering support--feel free to click my name and find your way to my mail in repair biz.
jessa