The Z1s cannot be Bootlader Unlocked, but maybe you are lucky one, type *#*#7378423#*#* on keyboard phone and see what saying. Bootlader Unlock Allowed: Yes or No, if No it can't be unlocked and there is no way around. For the rest is not the same model like C6903 then anything what you want to flash on it or get root, have to be for that model only.
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My Evolution: Sony Xperia Z1, HTC HD2, HTC Diamond 2, HTC HD Blackstone, Nokia 7070 Prism, Qtek 9100, Nokia 3100, Motorola T720i, Nokia 3310, Sony Ericson PF 768 (Blue)