aqui esta un identify y un log del proceso gracias por la pronta ayuda
SIGNED MODE (USING SERVER).
ChipID:C802,EMP protocol:0401

PHONE IS RED RETAIL PRODUCT
FLASH CID detected:52
OTP LOCKED:1 CID:52 PAF:1 IMEI:35893701043070 CERT:RED

Model:Z750a
MAPP CXC article: R1DB005 prg12008755_ATT_DA
MAPP CXC version: R1DB005
Language Package:CINGULAR
CDA article: 1201-9202
CDA version: R32A
Default article: 1200-8914
Default version: R1DB005
PROVIDER: 000-00
Network LOCKED

SECURITY UNITS BACKUP CREATED.
Elapsed: 9 secs.


SIGNED MODE (USING SERVER).
ChipID:C802,EMP protocol:0401

PHONE IS RED RETAIL PRODUCT
FLASH CID detected:52
OTP LOCKED:1 CID:52 PAF:1 IMEI:35893701043070 CERT:RED
LDR:2008-01-28 16:34 CXC1250843_DB31XX_CS_LOADER_ACC_SDRAM_R2A055
LDR CAPS:SYSTEM FLASH
LDR:2008-01-28 16:36 CXC1250780_DB31XX_CS_LOADER_APP_SDRAM_R2A055
LDR CAPS:SYSTEM FLASH GDFS FILESYSTEM TA
Phone not supported in that mode
Unlock FAILED
Elapsed: 9 secs.

tengo seleccionado en settings "signed mode" y "enable alternative security bypass"