Let’s try to install Nvflash on an Asus Transformer pad. Nvflash is a special bootloader, which protects that very bootloader from firmware flash accidents, which may turn you tablet to a brick.
A brick is a situation when you can’t restore you device anymore, essentially turning your pad to an expensive piece of silicon. A common trait of all hacker solutions, the instructions are minimal and require the user to know a lot. If you don’t, you’ll have to spend many hours online trying to gather information piece by piece. So, what will you need? First, enable USB debugging on your tablet. Next, use the official Asus utility to unlock your bootloader, which I described in another post. It’s worth mentioning, that even this is official utility, it voids you warranty. It is considered that you can’t lock your bootloader again, however, some forum posts say it’s tricky but possible. You also need special USB drivers, download them. Get Nvflash on the same page. You will also require a mysterious fastboot. It turns out this is a part of Android SDK, but if you don’t want to download the whole package, just get fastboot separately. So you have four folders: drivers, fastboot, nvflash and wheelie. For convenience, put files from the latter free into a single location. Now turn off your tablet, then power it on again, holding volume down button. In the left upper corner Checking for RCK image will appear, and then 3 icons in the middle of the screen. Using volume down, select the USB icon, and then press volume up to confirm.
You’re now in fastboot mode. Windows doesn’t have drivers for this mode of course, so go to Device manager and manually point it to the path where you extracted the downloaded drivers. Now a fastboot device should appear in the Device manager. So, now open command prompt in the folder where we merged three folders together, and enter the following command
fastboot -i 0x0b05 flash staging ebtblob.bin
only to get Signature mistmatch error.
It turns out there was an update from Asus, which did not install Jelly Bean, while adding signature check to the bootloader. That 4.0.3 firmware version 9.4.5.30 . In other words, this version introduced signature check: from now on, to update you bootloader the update file must be signed by Asus. That’s exactly the same way game console manufacturers prevent users from running unsigned, homebrew applications. Needless to say, the custom bootloader we’re trying to flash is not signed by Asus. Neither are previous official firmwares prior to version .30 , since signature check was introduced in this version only. That’s why you can’t downgrade to an earlier bootloader. Deadend.
So, on one hand, Asus officialy issues a way to unlock your bootloader, like, guys do whatever you want, but this void your waranty, which is somewhat fair. On the other hand, Asus releases a software update effectivly blocking all non-Asus bootloaders from installation. So, by unlocking your device, you’ve lost you warranty and gained nothing, since it is still locked to Asus-only software. So basically Asus is heading full speed the way already pioneered by Apple, Sony and other copyrasts. That’s sad and indescent. So, what to do now? Well, let’s at least install Jelly Bean. Since we unlocked our device and OTA updates are not available for us anymore, we’ll have to flash complete image, which is even better in the long run. You may flash it with fastboot, but’s its much easier to flash from a microSD memory card. First, download the update from Asus website. It’s a archive, which has another archive inside, which has blob and metadata. Unpack it only once, leaving the second archive inside untouched. Copy it as a zip to the root of the memory card, power off the tablet, insert the card and power on the device. Now select update from the notifications list and confirm it. Updating will take about 5 minutes. A quick check – the update was a success. If you got problems with keeping root, add Clockwork Mod recovery to the fastboot folder, copy SuperSU to you device, flash ClockWorkMod recovery and use it to install SuperSU. If you’ve lost flash, just get it from Adobe website and install as a package.