I have two Sony Z3 compact mobile phones and on one camera died after it fell to ground (it was guarded by plastic case) so I searched for solutions on Internet and found nothing helpful. Decided to give it to my friend so he took camera from a working phone to broken one. Camera was still not working, so the problem was in motherboard. I decided to sell it as camera was important for me but another friend (thx. Daj Hard) saw my ad and told me to check some Russian site that managed to get it working. There are even few youtube videos like this one or this one and that is the only way to fix black camera issue on Sony Z3 compact.
Here is a pictures of my own “fix”:
And here is a picture taken with same phone and fixed camera few days ago: