Try a forced Safe Mode start by pushing power and vol-down and hold it for a while.
This probably won't work.
You can also try to push power and vol-up simultaneously and holdit for abot 20 seconds.
This probably won't work either.
Use Xperia Companion to do a software repair.
As you cannot access your device, all data will be lost.
Switch off your phone, tick the "device cannot be recognised or is a smart watch" and follow the instructions.
Good luck repairing your device!
