problem at booting

[Ilya_s]

Hello.
Today I wanted to do a software update (from 5.0.2 to 5.1) device XPERIA Z, and came across several times "error 100" at the beginning of the update.
I tried to restart the computer and the router several times.
The third time I try to do a software update I encountered "error 100", but this time by a software update in the middle.
Then I tried to turn on my device and then I come across a post on my device screen update fails and the device can not start.
What should I do and how I fix this problem?
Thanks in advance.
ILYA

[Thommo · Accepted solution]

Try performing a system repair using PC Companion - This will factory reset your phone and erase all data

Switch off your phone and unplug from Pc (Hold volume up and power for around 10 seconds)
Start PC Companion and select Support zone then Update my phone/tablet then in Blue Repair my phone/tablet and follow the on screen instructions - When prompted connect your phone still switched off holding volume down or back button - This should start the repair or reformat process

If you are using Windows 8/8.1 or a 64bit operating system then adjust the settings for PC Companion and run in compatibility mode and chose Windows 7 or XP

[enver]

It seems that the update to android 5.1 causes different problems than the upgrade to 5.0 earlier this year (which was a total disaster).

So my question is how I can turn off the messages that ask me to update? I don't want to go through yet another factory reset an reinstalling all my apps.