Galaxy S5 :: Suddenly Will Not Turn On

My brother has a S5 from Verizon that is about a year and a half old. He's been using it with no problems. Woke up at about 2:30am and it was working fine but at 7am it was dead. It will not turn on, has no lights present, nothing. We've tried to restart it using the volume, lock, and power keys. We've taken the phone apart and looked at all the parts. Verizon ran a online check of some sorts and says it's nothing in their system. We know the battery and sim card works because he is using it in my dad's S5. We wouldn't worry about the phone so much but he has pictures of his son on there. He had some left on it before he started using a sd card.