ADB detects but, fastboot does not detect device in windows 10

Question

I am trying to root my phone. I have flashed TWRP recovery from here using Odin. I have installed Android Studio for Android SDK. The command adb devices shows the device connected but fastboot devices just gives me a blank. I have searched for solutions but most of them suggested to install drivers. I have installed the drivers suggested whenever applicable but, the result did not change. I have this issue too, when I select Apply update from SD card in custom recovery I get the following error

E:failed to mount /sdcard (No such file or directory)

The solution suggested in many sites to side step the above error was to use adb and fastboot. Please help me solve this issue.

My Phone Info:

• Samsung Galaxy S6 Edge
• Android 6.0.1
• SM-925T
• G925TUVU4EPF1

Answer 1

I guess the problem is that you are still using the stock-recovery as it seems.

Apply update from SD card is typically used in stock-recoveries.

TWRP typically looks like this: ^{Thanks to Technobuzz for this picture}

So again you have to follow this procedure for the Galaxy S6 Edge on Android 6.0.1:

1. Download TWRP 3.0.2.0 from their official site and place it on your desktop.
2. Download Odin3 from here and extract it to your desktop. It is a german site - but the download starts after 3 seconds and is clean atleast.
3. Make sure Samsung Kies is not running, then start Odin with administrative privileges.
4. Add the downloaded TWRP file under AP / PDA in Odin.
5. Boot your phone into download mode (volume down + power button), then confirm the dialouge by pressing the volume up button and connect it to your pc via USB.

Your setup should look something like that (don't mind the filename) : ^{Thanks to pocketpc.ch for providing this image}

Then start the flashing process, wait until Odin says PASS! in its message box. Then reboot your phone into the recovery mode and you should be good to go.

If this procedure does not work for you, repeat the process but untick the Auto Rebootcheckbox before flashing. Then manually reboot by holding the power-button for like 5 seconds and try booting into the recovery.

Further Readings:

1. HOW TO: Install TWRP 3.0.0 Recovery on Samsung Galaxy S6 Edge

Answer 2

For most Android devices, there is a fastboot menu with and image of an open Android and some options. Accessing it usually involves turning on the phone while pressing one or both of the volume buttons. However, Samsung devices have it differently.

Instead of using fastboot, you use Odin. (These instructions are for a galaxy tab 3, might vary by device.) If you turn on the phone while pressing home and vol down, you enter download, or if you used Odin before, Odin mode. This is used instead of fastboot to flash Roms.

There are many videos on how to use Odin to flash Roms like CWM and TWRP, so search for one of those.