I am having the EXACT same problem as this guy. I am also stuck on the yellow triangle screen in TWRP 2.0. I have spent the last two days trying to unbrick my Kindle Fire, and although I have learned a TON of stuff about adb and fastboot, the minute I think I'm figuring it out, i get stuck again. Here's what happened:Okay nevermind. It is charging now! Ill let it charge for about an hour or so and then try the utility. I'll post back with an update on my device. Thanks for all the help guys.
Update - So now I think it is just fudgeing with me. It was charging, now It's doing the on/off thing again. I'm just going to request a new one. Chances are if nobody here can fix it, neither can they. Nor will they no what the fudge the boot image mean.
First, I rooted my KF with SuperOneClick to install Android Market. Worked perfectly. Well, being the idiot I am, I decided to try and put CyanogenMod 7 on it, and after about 6 hours worth of messing around, I got it working GREAT!! No problems, except I didn't have Android Market. So I tried installing Google Apps and Go Launcher EX from Kindle Fire utility, and the next thing I know it is stuck on the CyanogenMod 7 boot screen.
I started fresh today and was able to get off the CyanogenMod 7 boot loop by playing around with Fastboot and ADB for a while, but then found myself stuck on the Kindle Fire logo. Finally, I got past the KF logo and was able to enter CWM recovery, but it wouldn't open my update.zip file. I was stuck again until I realized that I had three folders that I'm working with. One called Android with the android-sdk/platform-tools, one called KindleFireRoot, and one called Public. They pretty much all contained the same files. When I realized that I had been working out of all three folders, i figured I was screwed for sure. Following all of the advice throughout these numerous threads online, I'm pretty sure most of the time I was in the android-sdk folder. I was able to push any file I wanted to the sdcard and view directories of the Kindle with ADB, also, but only through the KindleFireRoot folder.
Well, I decided to try and use TWRP 2.0 (which I couldn't get to install through the KF Utility) instead of CWM, After trying the push the file with adb from all three folders, I was finally able to get TWRP installed using the KindleFireRoot folder intstead, and I tried them all. So it booted up fine into TWRP and I tried applying update.zip, but no luck. Everytime I rebooted it, it just loaded up into TWRP home screen without me hitting the power button.
Well, since my nerves were shot and I was ready to give up, I just tried wiping and restoring to factory, and when it rebooted I was stuck with the yellow triangle saying "press power button for recovery". Now, I have the same problem as above, where my Kindle shows up in device manager when I plug it in, but only for a few seconds (and the power button shows orange). then goes away with no access to it in order to update driver. When it does pop up for the couple seconds, it says its still android composite, but just vanishes. I also no longer have fastboot or adb access. I've tried everything and am at my wits end!!
I just want to get it back to factory now, it was a gift and I feel bad for messing with it in the first place, but I just can't help it. ANY HELP IS MUCH APPRECIATED!!
EDIT: Siiting down with the KF again, I found that if I turn it on by plugging it into the usb, it shows up in device manager as Android Phone three times, but only for about 3-5 seconds each time. Well, I figured that since it was showing up for at least that little of time, I should be able to push files to it during that time. I proved this by using fastboot reboot at the precise time it was showing up, and it worked, but only back to yellow triangle. It will also show up in devices with fastboot, but the serial number reads 0123456789ABCDEF, and only if I run the command in the short time that it shows up in device manager. So, obviously I wiped the thing, I new that already, and the serial number kind of confirms that, I think. I'm just hoping that there is a way to get it out of recovery in fastboot since I still have access, albeit a very short time, cuz if I'm correct, I need adb access to push files over to it, right? So here I go tinkering again, wish me luck. Anyone with ideas, please help!!