The phone is running:

SM-G390F

Android version : 7.0
Baseband version: G390FXXU1AQI2
Build number    : NRD90M.G390FXXU1AQI3

Root Device

• Download Boot & Recovery image from CF-Auto-Root for this device: ​https://desktop.firmware.mobi/device:289
• Enable Developer Mode' Settings -> About Phone -> Software Information -> tap 'Build Number' 7 times.
• Enable 'OEM Unlocking' in 'Settings -> Developer options'
• Reset device to factory default
• Put device in Download Mode by Powering it while holding down this keys: Power + Volume Down + Home.
• Retrieve PIT or download attached file sudo /usr/local/bin/heimdall download-pit --output SM-G390F.pit
• Use Heimdall to install new images: sudo /usr/local/bin/heimdall flash --pit SM-G390F.pit --RECOVERY recovery.img --BOOT boot.img
• Reboot phone and rooting will be done automatically

Removing factory applications

I do not like all Samsung and Google Applications which comes by default with the phone. It collects too many data, runs in background consuming CPU, memory and thus battery power consumes storage space.

• Disable 'Play Store' automatic updater
• Disable all applications which are not needed. Restoring their stock versions if needed.
• Use a Application called ​Applications Info located in ​F-Droid package manager to find locations of applications to be deleted.
• Delete using CLI: $ adb shell $ su $ mount -o rw,remount /system $ rm -R /system/app/application-to-be-removed $ rm -R /system/priv-app/application-to-be-removed

file:/system is read-only be default. use mount -o rw,remount /system to make it writable.

Original firmware

Can be found at ​http://samsung-updates.com/device/?id=SM-G390F

70876  tar tf AP_G390FXXU3BRL1_CL14164118_QB20918105_REV00_user_low_ship_meta.tar.md5
70877  tar tf BL_G390FXXU3BRL1_CL14164118_QB20918105_REV00_user_low_ship.tar.md5
70878  tar tf CP_G390FXXU3BRK1_CP11207705_CL14164118_QB20646500_REV00_user_low_ship.tar.md5
70879  tar tf CSC_DDX_G390FDDX3BRL2_CL14941370_QB20958994_REV00_user_low_ship.tar.md5
70880  tar tf HOME_CSC_DDX_G390FDDX3BRL2_CL14941370_QB20958994_REV00_user_low_ship.tar.md5
70881  ls
70882  tar xf *.md5
70883  tar xf AP_G390FXXU3BRL1_CL14164118_QB20918105_REV00_user_low_ship_meta.tar.md5
70884  ls
70885  tar xf BL_G390FXXU3BRL1_CL14164118_QB20918105_REV00_user_low_ship.tar.md5
70886  tar xf CP_G390FXXU3BRK1_CP11207705_CL14164118_QB20646500_REV00_user_low_ship.tar.md5
70887  tar xf CSC_DDX_G390FDDX3BRL2_CL14941370_QB20958994_REV00_user_low_ship.tar.md5
70888  tar xf HOME_CSC_DDX_G390FDDX3BRL2_CL14941370_QB20958994_REV00_user_low_ship.tar.md5
70889  ls
70890  less XCOVER4LTE_EUR_OPEN_HIDDEN200M.pit 
70891  ls
70892  vim boot.img.lz4 
70893  ls
70894  heimdall 
70895  heimdall print-pit --file ~/SM-G390F.pit 
70896  unlz4 
70897  ls
70898  unlz4 boot.img.lz4 
70899  ls
70900  unlz4 *.lz4
70901  ls
70902  unlz4 cache.img.lz4
70903  unlz4 cm.bin.lz4
70904  unlz4 hidden.img.lz4
70905  unlz4 modem.bin.lz4
70906  unlz4 param.bin.lz4
70907  unlz4 recovery.img.lz4
70908  unlz4 sboot.bin.lz4
70909  unlz4 system.img.lz4
70910  unlz4 userdata.img.lz4
70911  heimdall print-pit --file ~/SM-G390F.pit 
70912  history 

37029  ./bin/heimdall
37056  cd build/heimdall
37062  ./heimdall-frontend 
37067  heimdall-frontend
37071  heimdall --help
37072  heimdall print-pit
37073  heimdall --help
37074  heimdall print-pit --file ~/S7710.pit 
37075  heimdall print-pit --file ~/S7710.pit  | less
37114  heimdall 
37116  heimdall flash --pit ~/S7710.pit --STEboot1 ./STE_boot1.img --STEboot2 ./STE_boot2.img --Modem ./modem.bin --Kernel ./boot.img --Kernel2 ./recovery.img --SYSTEM ./system.img --CACHEFS ./cache.img --HIDDEN ./hidden.img  
37117  sudo heimdall flash --pit ~/S7710.pit --STEboot1 ./STE_boot1.img --STEboot2 ./STE_boot2.img --Modem ./modem.bin --Kernel ./boot.img --Kernel2 ./recovery.img --SYSTEM ./system.img --CACHEFS ./cache.img --HIDDEN ./hidden.img  
37119  sudo /usr/local/bin/heimdall flash --pit ~/S7710.pit --STEboot1 ./STE_boot1.img --STEboot2 ./STE_boot2.img --Modem ./modem.bin --Kernel ./boot.img --Kernel2 ./recovery.img --SYSTEM ./system.img --CACHEFS ./cache.img --HIDDEN ./hidden.img  
37121  heimdall --print-pit --file ./S7710.pit 
37122  heimdall print-pit --file ./S7710.pit 
37123  heimdall print-pit --file ./S7710.pit | grep -e 'Partition' -e 'Flash Filename'
37124  heimdall print-pit --file ./S7710.pit | grep -e 'Partition Name' -e 'Flash Filename'
37125  heimdall print-pit --file ./S7710.pit 
37126  heimdall print-pit --file ./S7710.pit | grep -e '---' -e 'Partition Name' -e 'Flash Filename'
43779  heimdall
43780  heimdall print-pit
43781  sudo heimdall print-pit
43782  whereis heimdall
43783  sudo -E heimdall print-pit
43784  sudo /usr/local/bin/heimdall print-pit
43785  sudo /usr/local/bin/heimdall download-pit
43786  sudo /usr/local/bin/heimdall download-pit --output SM-G390F.pit
43788  sudo /usr/local/bin/heimdall print-pit --file ./SM-G390F.pit 
43789  sudo /usr/local/bin/heimdall 
43790  sudo /usr/local/bin/heimdall 
43791  sudo /usr/local/bin/heimdall print-pit --file ./SM-G390F.pit 
43792  sudo /usr/local/bin/heimdall flash --RECOVERY /home/rick/recovery.img --CACHE /home/rick/cache.img 
43793  sudo /usr/local/bin/heimdall flash --pit /home/rick/SM-G390F.pit --RECOVERY /home/rick/recovery.img --CACHE /home/rick/cache.img 
43796  sudo /usr/local/bin/heimdall print-pit 
43797  sudo /usr/local/bin/heimdall flash --RECOVERY /home/rick/recovery.img --CACHE /home/rick/cache.img 
43798  sudo /usr/local/bin/heimdall flash --pit /home/rick/SM-G390F.pit --RECOVERY /home/rick/recovery.img --CACHE /home/rick/cache.img 
43802  sudo /usr/local/bin/heimdall flash --pit /home/rick/SM-G390F.pit --RECOVERY /home/rick/recovery.img --CACHE /home/rick/cache.img 
43815  heimdall
70848  history  | grep heimdall

}}}}