[Transformer TF300T Q&A, Help & Troubleshooting] pjc21:
There are a couple of ways to do this. As you said your running CROMi-X DEODEX, 4.2 bootloader (twrp 2.4.4.0-4.2 or 2.5.0.0-4.2) - so example below to flash latest stock asus JB 4.2 firmware for tf300t model - TF300T-WW_epad-10_6_1_15_3-UpdateLauncher.zip.

Method 1: - Using TWRP

Download the asus firmware zip - TF300T-WW_epad-10_6_1_15_3-UpdateLauncher.zip

Unzip this to a folder and inside you will find another zip called WW_epad-user-10.6.1.15.3.zip - Copy this zip file to your microSD.

Insert microSD in tab and reboot to twrp recovery, flash the WW_epad-user-10.6.1.15.3.zip , reboot, Done :good: You will now be on stock asus firmware, stock recovery & stock kernel.

Method 2 - Using fastboot - Assuming here android-sdk is installed and fastboot & adb working.

Download the asus firmware zip - TF300T-WW_epad-10_6_1_15_3-UpdateLauncher.zip

Unzip this to a folder and inside you will find another zip called WW_epad-user-10.6.1.15.3.zip

Here I put a copy of the WW_epad-user-10.6.1.15.3.zip on my micro SD card

On PC unzip WW_epad-user-10.6.1.15.3.zip and you will find a "blob" file- this is the system blob file for that firmware which is the system, stock recovery, kernel & bootloader all rolled into a one blob file.

Copy this blob file to your android-sdk/platform-tools folder

The version of TWRP you need for the JB 4.2 - 10.6.1.15.3 bootloader is "openrecovery-twrp-2.5.0.0-tf300t-4.2.blob" - flashing a non-4.2 version of TWRP or any version of CWM will brick device. Not sure if 2.4.4.0-tf300t-4.2 works on 10.6.1.15.3 bootloader.

So download "openrecovery-twrp-2.5.0.0-tf300t-4.2.blob" and also put this in android-sdk/platform-tools folder - you can rename it to something shorter if you want, say twrp-2.5.0.0-4.2.blob

Now connect tab to pc and boot to fastboot and check that pc can see your device ok

fastboot devices

should see device s/n here, if ok we can flash the system blob we put in the platform-tools folder

fastboot -i 0x0b05 flash system blob

This will take 10ish minutes, it will send file then write file and you should a blue progress bar on tab when it starts to write.

When complete

fastboot reboot-bootloader

You should now check & confirm that your bootloader has upgraded, look at the text in the top left of the bootloader screen and make sure it now has 10.6.1.15.3 in the text.

Here you should really be able to just reboot the tab and be fine but I would get stuck at boot animation so next part is a second flash of the same firmware but via TWRP recovery instead of fastboot, so method 1 - but you now have stock recovery so we need to flash TWRP first.

So in fastboot flash the "openrecovery-twrp-2.5.0.0-tf300t-4.2.blob" I shortened to "twrp-2.5.0.0-4.2.blob"

fastboot -i 0x0b05 flash recovery twrp-2.5.0.0-4.2.blob

again here you should see a blue progress bar on your tab

When done reboot to bootloader again

fastboot reboot-bootloader

This time select the RSK icon and boot TWRP recovery. In recovery I do a full wipe then follow method 1 and flash the WW_epad-user-10.6.1.15.3.zip from microSD, reboot & done :good: - You will now be on stock asus firmware, stock recovery & stock kernel.

If you need any more help just ask or have a look at my how-to in sig below for more info.