Peter from Hong Kong writes
My Sony Xperia Z3 phone is frozen. I cannot switch it on or power on. I have long pressed the power button multiple times, but nothing happens. Just the black screen. It was working fine just an hour ago. In my notification area I was prompted to update my Sony Xperia Z3 operating system and I happily obliged. After it seemed that the operating system had updated, the phone screen simply went blank. This is the new phone and I am panicking.
No need to worry. The Sony Xperia line of phones has this problem of phones freezing and people not being able to switch their phones back on or cannot power on. All you need to do is, simulate a battery pull. What it means is, you need to tell your Sony Xperia mobile phone that you are pulling out the battery and putting it back without actually physically doing it. Here is how to do it
Simultaneously press the Volume Down button and the Power button for 15-20 seconds. The highlighted expressions are important. Your phone should be able to restart.
For some models, the Volume Up button and the Power button combination works so you may have to try that in case Volume Down button does not work for you. In 90% of the case your phone should be fine after this. If it still doesn’t work, you may have to physically take out the battery, put it back, and try restarting the phone.