can't flash stock firmware neither twrp

Hi,
i recently bought this galaxy s6 i think it's from wind mobile italy
when i try to turn on it gives me "this device is locked because of an abnormal factory reset"
i looked in a couple of threads and i found that i should downgrade to 5.1.1 in order to access to phone
what i did ?
1-download 5.1.1 firmware and odin
2-try to flash via odin (PA)
it gives me this : "sw rev check fail device 3 binary 2" (failture)
3-then i tryed to install twrp via odin
and it gives me this :"custom binary blocked by r/l"

btw this is what i found writen in download mode :
____________________________________
-odin mode
-product name : SM-G920F
-current binary : samsung official
-system status:official
-reactivation lock : o,
-secure download: enabled
-knox warany void 0 (x0000)
-rp swrev b:3 k:2 s:2
___________________________________

please help me im stuck here :(

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