Unable to update using RUU HTC One (M7) AT&T

I have bought a used HTC One (M7) that is AT&T unlocked. Now I live in Tunisia (North Africa) and i can't update my software version "4.18.502.7".
This is my bootloader status:
***RELOCKED***
M7_UL PVT SHIP S-OFF RH
CID-11111111
HBOOT-1.56.000
RADIO-4T.24.3218.09
OpenDSP-v32.120.274.0909
OS-4.18.502.7
eMMC-boot 2048MB

I tried to install the following RUU: "RUU_M7_UL_L50_SENSE60_MR_BrightstarUS_WWE_7.17.15 40.7_Radio_4T.35.3218.16_10.33Q.1718.01L_release_4 20191_signed_2"

I had changed my cid to match that of Brightstar (BS_US001, or sth like it) but didn't work. I kept encountering "error 155".
I just want to find a compatible RUU and to be able to update (getting rid of AT&T bloatware would be a plus).
Thank you!

Download from this link