S6 Edge+ (G928) t-mobile Downgrade problem

Hi,
My cell g928t on MM6 got frp, and all methods fail, now i want to downgrade to 5.11, but when i try to flash (G928TUVU1BOH4_G928TTMB1BOH4_G928TUVU1BOH4_HOME.ta r) it, i get error
"SW REV CHECK FAIL "
what to do? how to downgrade
any help plz?

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