The sd card needs to have at least 4GB free

Extract downgrade(BTV-DL09).zip and place the dload inside directly under the sd card and insert it into the d-01j.
Put the original oeminfo on the sd card.
(At this stage, you can also extract BTV-L0JC137B032_Firmware_Japan_NTT DOCOMO_Android 6.0_EMUI 4.1_05014HWX.zip, rename the dload to something else, and place it directly under the sd card)

Initialize with Settings→System→Reset Options→Erase All Data

Boot with TWRP

adb shell

dd if=/external_sd/oeminfo.img of=/dev/block/mmcblk0p8
↑This will return oeminfo to stock

exit

adb reboot bootloader
↑upStart fastboot with this

PHONE Unlocked Confirm FRP Unlock

Extract d-01j stock recovery.zip
fastboot flash RECOVERY.img and RECOVERY2.img

fastboot flash recovery recovery.img
fastboot flash recovery2 recovery2.img

Disconnect from the PC
Press and hold the power button, and when the screen disappears, press and hold the power button and volume + and -.

If you leave it alone, it will reboot three times and boot normally, so turn off the power.

Delete the dload in the sd card (the one you just used), extract BTV-L0JC137B032_Firmware_Japan_NTT DOCOMO_Android 6.0_EMUI 4.1_05014HWX.zip, and put the dload directly under the sd.
(Open to BTV-L0JC137B032_Firmware_Japan_NTT DOCOMO_Android 6.0_EMUI 4.1_05014HWX/Software/release/no-log to find the dload)

Turn off the power and press the volume + and - at the same time to return to stock Android 6.


The only way to upgrade to Android 7 is OTA.

If the update doesn't come down, insert the SIM, check for updates, unmount the sd card in storage, remove the SIM tray, reboot, and check again with it removed.

There have been three OTAs. Last build was 19021102.