Samsung GT-N900 IMEI null Unknown baseband

[Ransiri]

Phone came on Android 5.0 . I downgraded to 4.4.2 for repair. Try to write cert. But failed.
Here is the log

Platform: Samsung Android
Selected port: COM26
Selected model: SM-N900
Selected file: C:\QCN AND CERT\500_certs_qcn_\SM-N900_
359092050091226_S200012760.cert
Detected phone model: SM-N900
Firmware compiled date: Mon Apr 14 19:38:54 KST 2014
PDA version: N900XXUDND1
CSC version: N900OJVDND1
SW version: Unknown
Phone IMEI: Unknown
Android version: 4.4.2 (KOT49H)
Checking Root:
Phone is Rooted.
Reading security backup, please wait...
Backup saved as C:\Program Files\Octoplus\Octoplus_Samsung
\BACKUP\Security-SM-N900-Unknown07-08-2015_17-12-57-.asec file
Phone will restart now. Please don't disconnect cable!
Perform the following steps:
1. Connect phone via UART cable to the Box.
2. Note: phone screen must be active
Connecting to phone, please wait...
Writing Certificate failed
-----------------------------------------------------------------------------------
Platform: Samsung Android
Selected port: COM26
Selected model: SM-N900
Selected file: C:\QCN AND CERT\500_certs_qcn_\SM-N900_
359092050091226_S200012760.cert
Detected phone model: SM-N900
Firmware compiled date: Mon Apr 14 19:38:54 KST 2014
PDA version: N900XXUDND1
CSC version: N900OJVDND1
SW version: Unknown
Phone IMEI: Unknown
Android version: 4.4.2 (KOT49H)
Checking Root:
Phone is Rooted.
Reading security backup, please wait...
Backup saved as C:\Program Files\Octoplus\Octoplus_Samsung
\BACKUP\Security-SM-N900-Unknown07-08-2015_17-20-06-.asec file
Phone will restart now. Please don't disconnect cable!
Perform the following steps:
1. Connect phone via UART cable to the Box.
2. Note: phone screen must be active
Connecting to phone, please wait...
Writing Certificate failed

Is there a solution to wtite default EFS? I saw some product has this solution. Octopus possible to solve this?

[Octopus box]

Hello.

As You can see from your Software log, phone's modem part is damaged:

SW version: Unknown

This can be Software (modem firmware or EFS is damaged, or You have written unsuitable firmware) or HW problem.

You should re-flash the device with different firmwares and check, whether modem is correct (not Unknown). It is not possible to repair IMEI, if phone's modem part is damaged.

If after of writing all firmwares, which You have, phone's baseband is still null or unknown (SW version is Unknown) - most likely, this is HW problem (problem with eMMC flash chip).