[Moto E4 Plus Guides, News, & Discussion] arunps:
I'M NOT RESPONSIBLE IF YOU BRICK YOUR DEVICE, this worked for me and I'm sharing what I found, these are the steps to fix unknown baseband and null imei on XT1771. Please read everything carefully.

Software Necessary:

SP_Flash_Tool_5.1628_M2 : https://androidfilehost.com/?fid=962187416754471740

SN_Write_Tool_v1.1828.00 : https://snwritetool.com/download/sn-write-tool-v1-1828

Maui META - 9.1724.25.00 : https://allmobitools.com/downloading-maui-meta-3g-4g-imei-repair-tool/

Android Gadget CDC driver : https://gsmusbdrivers.com/download/android-cdc-driver/

PdaNet+ for Android : http://pdanet.co/a/

MediaTEK VCOM Driver : https://androidmtk.com/download-mtk-usb-all-drivers

Moto USB Driver : https://xdaforums.com/showthread.php?t=2550635

Programutag For XT1770, XT1771, XT1772 & XT1773 : https://mega.nz/#F!VtVXyChQ!7bTJ0kfa77-WDmWdDRhsjQ

ADB Fast Boot or Minimal ADB & Fastboot : Google it and install

Firmware:

XT1770 Nicklaus(NMA26.42-82)BY GD_Mekail92 ROM : https://drive.google.com/uc?id=0B92ccSPyf_fJU3V2QmhhZ3B4ZVk&export=download

Password: XT1770/GD Mekail92 [MENTION=7841024]Gsm dev[/MENTION]elopers

NOTE: Install two numbers of SIM cards before starting the procedure:

Procedure:

00. Extract and replace all files from Moto E4 Programutags to NICKLAUS_NMA26.42-82_subsidy-UNLOCKED_model_CFC_SVC.xml.

01. Install all required drivers after downloading from the above links.

02. Open SP flas tool and select MTK_AllInOne_DA.bin as download agent & MT6737M_Android_scatter.

03. Select Format All + Download and press download. Connect the phone @ switch off mode. Wait for flash to complete. Disconnect the USB Cable.

04. Dont switch on the phone. Select download only after selecting MT6737M_Android_efuse_only Scatter. Press download button & connect the USB cable. Disconnect the USB cable after flashing.

05. Dont switch on the phone. Select download only after selecting MT6737M_Android_lk_only Scatter from LK folder. Press download button & connect the USB cable. Disconnect the USB cable after flashing. Switch on the phone and it will boot as special boot loader mode.

06. Open hwflash.bat and wait for the procedure to complete. Open programutags_XTXXXX_XXXX_XXXX_SIM.bat and select the version of your mobile and wait for the procedure to complete. In our case we use programutags_XT1771_EMEA_Dual_SIM.bat and select C. ( If the command prompt closed quickly check your adb fast boot settings )

07. Open SP flash tool, select download only after selecting MT6737M_Android_lk_only Scatter from the root folder ( NICKLAUS_NMA26.42-82_subsidy-UNLOCKED_model_CFC_SVC.xml ). Press download button and press and hold the power button. Release the power button when the phone got switched off and wait for the flash to complete.

08. Switch on the phone and the phone will be ready with two sims as INVALID IMEI & with NVRAM error ( WIFI )

09. Open Maui META - 9.1724.25.00 and follow the steps from https://androidrookies.com/how-to-use-maui-meta-3g-v6-to-restore/ to restore imei. Note: Recommended to use your own imei number. Use BPLGUInfoCustomAppSrcP_MT6735_S00_GEORGE_AP_V36_1_lwg_1 from NICKLAUS_NMA26.42-82_subsidy-UNLOCKED_model_CFC_SVC.xml folder.

10. Switch on the device. IMEI will be ready.

11. Open SN Writer and follow the steps from https://androidmtk.com/use-sn-write-tool to restore your mac and bluetooth address. Deselect IMEI and select BT Address & WIFI Address Only. Use BPLGUInfoCustomAppSrcP_MT6735_S00_GEORGE_AP_V36_1_lwg_1 & APDB_MT6735_S01_alps-mp-n1.mp1_W17.27 from NICKLAUS_NMA26.42-82_subsidy-UNLOCKED_model_CFC_SVC.xml folder.

12. After all, we successfully fixed the unknown base band and null imei including OTA Updates.

:good::good::good::good::good:

Known Errors:

None

Notes:

Hope this may help to solve above problems of all Moto E4 Plus users with MT6737 chipset

Thank You...

All credits to

XDA Develpoers