Answer to "My Xperia Z5 premium doesn't turn on, and the red led flashing"I had a similar issue, couldnt fastboot, POWER+VOLUME KEYS did nothing for me. Changing the chargers had different effects from red flashes, 3 red flashes and at times white sony screen flashes. So I took it to the local shop and when they opened up the back cover, they found out that the battery connector had come loose. After pressing it back in, the phone was back. Hope this helps someone.