i have a i9300 with 4.3 that is sim locked on a carrier from my country. as far as i know, there are no free methods to unlock 4.3, but i read that 4.1.2 can be unlocked at home for free, or at least with galaxsim (it's not free but it's cheap ~ 3 euros). but i read that it isn't possible to downgrade to an older rom (the phone will brick/bootloop), is that true? i also saw that alot of people lost their imei. is it safe to try downgrading if i make a efs backup?
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Phone: SONY Xperia Z2
Android ROM: Stock+Root 4.4.2