Desperate error - Startup PIN code on my phone!

[Android Central Question]

Hi all!
This is my first post, but not for a happy reason.

Briefly, I took my Asus Zenfone 4 screen (broken) to exchange.

The technician (friend that I trust) asked me my unlock pass (PIN) and unlock screen pass too, to restart it for tests. He removed the passwords to work freely. Restarted the phone 2 times, everything ok.

The problem (a bit desperate) is that now, supposedly for no reason, we can't access phone. Says: To start your Android, enter your PIN (Pin, not password, just numbers). Seems like smartphone took a PIN itself.
We tried old PIN few times but says that 3 more attempts and the data will be deleted (!!).
(Note: I had App Lock installed and protected almost all important apps with the same Pin, but I think there's nothing to do with this problem).

The only solution will be reset the system?? Unfortunately I have some files without backup that I can't lose.
There is any original Pin?

Any help is welcomed! Thank you so much!

 

[B. Diddy]

Welcome to Android Central! The PIN to for that "start your Android" screen should be the same as the one for screen unlock. It shouldn't have suddenly created its own PIN. If your old PIN doesn't work, then I'm afraid you're out of luck. If the phone somehow did set its own PIN, that would suggest some major glitch in the firmware, which would mean your data was probably lost anyway -- sorry!