Samsung Galaxy J7 won't boot into bootloader.

[AC Question]

I had to root my brand new Galaxy J7 (SM-J710FN) to restore my previous data backed up with Titanium backup. I have my data back so i decided to do a nandroid backup as well with TWRP. However, the backup always failed stating this error "E: Failed to mount /data". I am not well versed with android and its commands and whatever little I know is only because of my consistent internet searches.
I decided to give up so I unrooted the phone and flashed the stock firmware. Now I want to check if the boot loader is locked. I am listing whatever problems I am facing right now.
1. Whenever I boot into recovery I always get “installing system updates” message and then I get to the recovery mode.
2. After selecting the option “Reboot to bootloader”. The phone gives an” E: Failed to mount /data (Invalid Argument)” error and restarts normally.
3. I have adb and fastboot installed on my pc. ADB works fine but fastboot commands draw a blank.
As of now I do not have any problems with the phone since its working as it should. Can some please explain the errors that I am getting in my phone?
Thank you!

 

[Rukbat]

"E: Failed to mount /data (Invalid Argument)" sounds like the recovery ROM (the hardware in the phone) is bad - the phone can't mount the partition, usually because it's not there. You could try reflashing the ROM (see [Samsung] How to flash Stock ROM via ODIN - it's more boring than difficult), but that may also throw a hardware error. (That would mean a new motherboard.)

 

[harshree]

"E: Failed to mount /data (Invalid Argument)" sounds like the recovery ROM (the hardware in the phone) is bad - the phone can't mount the partition, usually because it's not there. You could try reflashing the ROM (see [Samsung] How to flash Stock ROM via ODIN - it's more boring than difficult), but that may also throw a hardware error. (That would mean a new motherboard.)

Thank you for the reply. Your guess was right. I still get the "E: Failed to mount /data (Invalid Argument)" after flashing the stock ROM again. My phone is already warranty void (rooting and all) so a new motherboard would be trouble. I guess i do not want to mess up further. I have no issues using the phone normally. I would be relieved if you would confirm that this error won't bother with the normal functions of the phone. Thanks.