2006 xc90, 4.4 liter v-8. Rear entertainment system is not working, checked all connections and fuses all are up to par. I have power, yet it doesnt turn on the player or screens. All other electrical and navigation systems work great! A little help please.

You have power where? I assume you mean at fuse. I had the same problem on my 2006 XC90 and it ended up being the video controller below cup holder being bad. Someone that owned vehicle before me spilled liquid on it and it's not protected from spills. I got a used one off eBay.
I checked for power in and power out. Had no power out of this unit.