Write cert N910f Initialization AT RIL... error

[altavista_live]

Hi! My phone is blacklisted by operator, so I want to rewrite another cert file. When I try to do it, appears an error. Any idea?

This is the log of Z3X:

Operation: Write CERT
Selected model: SM-N910F
Selected port:
Software version: 26.3

Checking certificate file... OK
KEY ID: 0772
Waiting ADB device...
Please, allow USB debugging on phone... OK
Reading phone info...
Model: SM-N910F
Android version: 6.0.1
Product code: SM-N910FZKEITV
Phone version: N910FXXU1DPB1
PDA version: N910FXXS1DPE6
CSC version: N910FITV1DPE1
CSC country code: ITALY
CSC sales code: ITV
HW version: MP 0.900
Phone S/N: R58FC1HBRLB
Modem board: MDM9235
RF cal date: 2014.12.26
IMEI:
Initialization AT RIL... error
Done with Samsung Tool PRO v.26.3

[altavista_live]

I tried with other versions of samsung tool pro 20.5, 25.4, 26.3, 26.3.1, and latest 26.4). I tried to isolate middle contact of battery but no changes...
Sombody have an idea about it?

[altavista_live]

ok, thanks to all. I solve the problem. Maybe can help someone. I do this:

1 - downgrade android version from 6.0.1 to 5.1.1. I use N910FXXU1COI3 and flash all 4 files BL-AP-CP-CSC.
2 - reset MSL
3 - wrote cert file and all ok:

Operation: Write CERT
Selected model: SM-N910F
Selected port: COM33 SAMSUNG Mobile USB Serial Port
Software version: 26.4

Checking certificate file... OK
KEY ID: 0772
Waiting ADB device... OK
Reading phone info...
Model: SM-N910F
Android version: 5.1.1
Product code: SM-N910FZKEBTU
Phone version: N910FXXU1COI3
PDA version: N910FXXU1COI3
CSC version: N910FBTU1COI1
CSC country code: UK & IRE
CSC sales code: BTU
HW version: MP 0.900
Phone S/N: R58FC1HBRLB
Modem board: MDM9235
RF cal date: 2014.12.26
IMEI:
Initialization AT RIL... OK
Bypass MSL... OK
Checking for compatible phone and cert... OK
Phone KEY ID: 0772
Writing CERT... OK
Checking CERT status... OK
Rebooting phone... OK

Done with Samsung Tool PRO v.26.4