Htc m9 unknown baseband

Cause:
I tried to convert M9 Ntelos to M9 sprint ,so I did s-off and cid 11111111 and flashed the phone with m9 sprint firmware ,but I got unknown baseband.
what I tried after:
revert back to s-on and write the original cid and flashed with original Ntelos firmware but the problem still the same .please how do I fix it :
Reading information…
Using Fastboot mode…
Reading common information
INFOkernel: lk
INFOproduct: htc_himawhl
INFOversion: 1.0
INFOimei: 990005694248312
INFOversion-main: 2.11.510.16
INFOboot-mode: download
INFOversion-baseband: 1.11.C1144030@50421
INFOversion-bootloader: 1.0.0.0000
INFOmid: 0PJA20000
INFOcid: ACG__001
all:
Reading secure flag information
… INFODevice security level S-ON
OKAY
Reading CID information
… INFOcid: ACG__001
OKAY
Reading MEID information
… INFOmeid: 9900056942xxxx
OKAY
Read information completed.