n900a baseband unknown imei null

Hi, I have a n900a (at&t note 3). The phone was upgraded via OTA to 5.0 (from 4.4.2) and got the null IMEI and unkn. bb problem.

I downgraded it again to N900AUCUCNC2 and root it. But when I try to write cert of n900, I got stucked to:

I tried doing Wipe EFS/NVM first, but still same result.

Tried doing reset MSL but got stucked saying:


Operation: Reset MSL
Selected model: SM-N900A
Selected port: COM39 SAMSUNG Mobile USB Serial Port
Software version: 26.6

Reading phone info... no answer from phone

Done with Samsung Tool PRO v.26.6

any help?