Black screen once booted

Hi everyone,

After a short visit into a swimming pool, my Z5 Compact had difficulties running (what a waterproof smartphone ...). I dismantled it, removed the water in it and let it dry. I reassambled it but I still have a problem.

When I power it on, the loading screen appears (Sony then Android) but when it's on the screen goes off. Sometimes I can see the lock screen for a few seconds, sometimes I don't. What annoys me is that the phone vibrates when I put my finger on the fingerprint reader, the same way it would vibrate when you try to unlock it as it it would be running fine.

Does someone have something in mind ?

Thomas