Can't enter my Android after theft alarm

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I have a strange issue.
Yesterday after Rebooting my phone (Xperia Z Android 4.3 I think) I had alarm that my Phone was stolen - dunno why. 
I turned it off, replaced SIM Card and turned on.
After that I had to enter PIN code to avast Anti-Theft and PIN to SIM Card (I remember them both for sure) but after that I'm asked for next code (what ??) and I'm able to make only Alarm calls.

I never used PIN Code Lockscreen in my phone, never set any PIN to acces my Android, always used switch lock.

Maybe it's not Adnroid issue but app that I use instead od standard lockscreen - Echo Notification Lockscreen ??

Any suggestion except flashing my Android ?? 

I'd prefer some manufacturer's code or so... if exists.

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OK, found solution 

In case anyone had similar problem I used Android Device Manager (webpage) and blocked my phone with new Password, which is necessary to unblock my phone now instead of PIN. And I can also change PIN for new one.

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After all I got access to my phone but I can't activate most of Screen Lock options as None, Switch, Face Unlock or Pattern unlock.
Got active only PIN and Password.

I've read that it can be security certificates issue, but don't know how to fix it on Android 4.3.

Any suggestions/ help ??

It's very annoying there's new problem on every step.... 

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Found solution again 

I turned off Avast AT as Device Manager and could without any problem change type of Lockscreen.
I changed for None and turned on Avast AT as Device Manager and everything works just like before and as I wanted