[Q&A] Unlocking My Phone (did not stole it, its mine)

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hi all, just recently bought a pocophone f1 from someone, its complete with box and proof of purchase, so, i confidently say that its mine. when i got it from him, its in beta rom, so i can still log into the phone without problem, even logged into my mi account. the problem starts when i wanted to move to stable rom instead. to my surprise, the phone need me to log into previous owner account which i do not the password of. and unfortunately, i cant access watsapp to contact the person. yes, its my only phone currently. tried mi website to unlock the phone with phone number and proof of purchase.. only to find out that my number country code isnt supported. is there another way to unlock my phone? please help, thanks

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