[Nexus 7 Q&A, Help & Troubleshooting] stickplayer:
[Q] New Nexus 7, Win 7, Nexus 7 Toolkit can't boot into Fastboot, "Too Many Links"

SOLVED!

So I went ahead, tried flashing the stock recovery, no joy (no recovery menu at all - just a bad-android image). After a while, tried flashing CWM touch (via Toolkit) - and now it's working. So, everything seems good now.

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UPDATE 5 - PARTIALLY SOLVED:

So, after the last couple of things, I began to suspect bad hardware, as I alluded in those updates. And I was right.

But... it wasn't the hardware you might have thought.

It was...

(this is embarrassing)

The USB cable.

Yes, the USB cable. It was the wild variations in recognizing the fastboot mode that made me suspicious. Replaced the USB cable with another one and... stability, achieved. Unlock, root, recovery program and SU program all went without a hitch. In fastboot mode, for the first time, the device serial number shows.

HOWEVER - things are not perfect. The recovery mode from the bootloader still gives the bad-android icon.

I just used the toolkit to reflash stock recovery back to the device. This completed rapidly, without error. I then tried the recovery option in the bootloader, but again, no joy.

So at this point, I point a finger partly at the tools used to flash this - they claim there is no problem, yet the flash doesn't take at all, and no error is given. As a sometimes firmware developer, I'm used to flash being followed up by a checksum or other test to verify success of the flash. Is that not being done (shame, if not). If it is, then apparently the flash works, but the software being flashed doesn't? The stock recovery???

Any ideas on how to get this back? I just did the full unlock, which wiped all user data, and proceeded from there. I now have a solid connection, but don't really know how to get things back.

Perhaps I need to manually reinstall 4.2.2?

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UPDATE 4:

So, on a lark, from fastboot in Android, I selected the "Recovery" option - it starts to boot that, then gives the Android with red triangle and exclamation point. So, looks like the recovery was toasted.

This was a brand new device earlier today. It has been completely wiped twice, and none of this has gone away. Seriously: bad device?

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UPDATE 3:

So, I thought I'd try the direct approach, as outlined here:

http://xdaforums.com/showthread.php?t=1741395

Device is in Fastboot, Device Manager shows it as ok.

I run fastboot flash recovery <file> -- and IMMEDIATELY get "fastboot has stopped working" - that's right, a hard crash in fastboot. And this is repeatable.

Am I wrong in thinking this looks more and more like a driver problem? I note that fastboot is recognized as a device maybe half the time - the other half, it gets an exclamation point in Device Manger. All I do then is restart the bootloader using the bootloader menu, and usually it fixes right up. But that's obviously a huge red flag, as the device should be recognized every time.

Is this a defective Nexus? The only thing that seems dicey is anything relating to fastboot/bootloader (which is, however, unlocked - or at least it says it is).

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UPDATE 2: Using the "restart bootloader" in fastboot results in slightly worse non-recognition of the device. When I do that, I get a straight "USB Device Not Recognized" from windows - the device manager doesn't even show "Android Phone" as a class of device in this case.

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UPDATE 1: I found the thread talking about missing entries in the INF file. I added these, and got a somewhat, but not entirely, stable recognition of the Nexus 7 when in fastboot mode. Basically, sometimes it is recognized, other times it is not. By "recognized", I mean that the Windows Device Manager shows the device as "Android Bootloader Interface", with no indication of a problem (which it only does in fastboot mode - it shows as a composite ADB device when booted normally).

However - it seems it fails to recognize fastboot about half the time, although it seems that that is related to reboots - that is, a fresh boot, then going to fastboot through adb seems to work. But restarting fastboot manually fails to be recognized (Windows shows a bang by the "Android Bootloader Interface", and says the device "failed to start").

So, using 4.3.5 Nexus 7 toolkit, I tried to unlock the bootloader. Windows recognized fastboot mode, but the process errored out anyway, after maybe 15 seconds, saying "Too Many Links" - the same error as before.

Again, brand new 32gb wi-fi-only Nexus 7, with 4.2.2 update and the most basic configuration only (dev mode, usb on, etc.)

Any ideas?

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ORIGINAL

So this is a new, out of the box nexus 7. The only setup has been to connect to wifi, update to 4.2.2, and enable developer mode and USB debugging.

Running latest paid-for toolkit - Update 29 Feb 13, version 4.3.5

Just about everything requires the insecure fastboot, but every time I try any operation that attempts it, I get:

Booting into fastboot mode

downloading 'boot.img' ...

FAILED <status read failed <Too many links>>

I basically can't do anything - in this case, I was trying to backup.

It is being done on 64-bit win7 system that had drivers, and worked for another nexus 7 a couple months ago. But, just to be safe, I uninstalled the drivers, rebooted, and installed.

However, I see this on the home page of the toolkit:

FASTBOOT MODE [If serial shows, drivers are installed]

List of Devices attached

ADB Mode

List of devices attached

<numeric code> device

From this, it seems I should expect the word "serial" to show up if the drivers are installed?

I then unplugged the Nexus, refreshed the menu, and both Fastboot and ADB show no devices.

I then plug in the nexus - I get the usual two tone "device attached" sound, no warning or error message from Windows.Checking the Windows device manager, I see a section "Android Phone" with the entry "Android Composite ADB Interface". There are no unknown devices, which would seem then that drivers are working.

So, another refresh of the main menu, and again, I see, under ADB MODE, a single device ID number, and the word "device".

I don't know what to make of this. Apparently, per the "if serial shows" message in the main menu, drivers a NOT installed. But according to Windows, they are.

This perhaps matches the fastboot failure.

Should I see "serial"?

In any case, what do I do to get the drivers to work properly if they aren't?

And if they ARE working, then what is wrong with fastboot?

At this point, I think the toolkit is broken, and worked a couple months ago.