Suddenly "No Signal" after Apple Logo Bootscreen.

This is what happened to me on my iPad2 3G when I tried to fix gcc-toolchain on it when I recklessly replaced libraries.
Of course you haven't touched the libraries at all in this case.

What actually happened is possibly a recovery loop.
If you still have your SHSH do the following, though I cannot guarantee this will work:

- Update your iTunes to the latest version
- Download the latest TinyUmbrella. (You should have this if you already tried saving your SHSH with it.)
- Close iTunes
- Start TinyUmbrella and run the TSS server.
- Open iTunes.
- Put your iDevice into DFU mode (Note: DFU mode is not recovery mode, it's stronger than recovery mode. If you see "Plug your device into iTunes", you are in RECOVERY mode. DFU mode is just a black screen and iTunes saying "iTunes detected a device in DFU mode"). <--- Trying to put an iDevice into DFU mode manually is a pain in the ass, so youtube it and just follow the video.
- Hold SHIFT and click restore
- Restore to a previous known working version.
- Now I'm not sure about this step, but if you get stuck after restore in recovery mode, use TinyUmbrella to kick your device out of recovery loop.
- Re-jailbreak, install XBMC -> profit.

Alternatively, you can try to update to latest iOS, and then downgrade it as a backup plan if the above steps fails.

Good luck and I hope this works! I kind of had nightmares of it since I restored my iPad 2 THREE times in one week because me wanting to install GCC on it (it succeeded after the third time ).

PS: If you could SSH into your device, it means that some core files got deleted or modified making springboard unable to launch. But the device boots just fine I guess. In my case, it was like the device didn't even want to boot. Of course unless you know exactly what has been modified/deleted and if you have a backup of those file(s), you can fix it. I doubt you would.

4.4 isn't signed anymore. I just tried that via Seas0npass. Too bad. I stil got the Shsh Blobs for 4.2.1 but I can't install it.

I just tried iFaith, the whole building of a signed firmware went fine, but again, even on my girlfriends PC I can't install the signed firmware on my apple TV. it just says someting like "preparing to restore iPhone (!)" but it never finishes. I'll try to update iTunes and try iFaith again. Any other options?

Are you sure to put it in DFU mode and not recovery mode? Because that makes a huge difference.
And the whole point of having SHSH is to ignore Apple signing your firmware, because the TinyUmbrella TSS server will fake the apple server and sign it for you.
Are you still on your broken iOS or updated to latest? If all else fails, you should update to latest iOS which apple signs and then try to downgrade. I know this downgrade stuff when your device is practically useless is bad for the heart.

Yes, I'm in DFU mode. Tiny Umbrella said so.

I'm still on the broken iOS. Upgrading to 5.X is something like my final option, since I don't know if I'll be able to downgrade.. or should I officially upgrade?

Just try playing around first if you can downgrade it like that. When you get tired of it, upgrade to last version and try to downgrade from there by putting device on dfu mode on the last version. I also did that from broken iOS 5.0.1 to 5.1 and then DFU downgrade to 4.3.3

mine does this as well, all i do is press and hold both small buttons and it 'resets' itself

Jailbreak FAQ and sticky post have been updated with re-jailbreaking 4.4.4 info.

I had this issue on one of my two ATV2s after upgrading to 4.4.4 (and thus re-jailbreaking it...) .. First one worked just fine, but when I did the second one - and plugged it in to the TV once it was all finished - I got to the "No signal" boot loop.

Unfortunately I don't have a specific fix for it. For me, I left it plugged in to the TV without really thinking about it (continuously rebooting) and started googling the issue e.t.c. ... and then after something like 30 minutes I saw a familiar sight in the corner of my eye. It had suddenly and spontaneously booted up and everything was working. Since then I've never had this issue again.

I don't know how long you've left it in the boot-loop state still connected to the TV .. but it might be an option to leave it trying to reboot for a couple of hours if you haven't done so already - and eventually yours might kick into gear like mine did.

.. The issue (along with how it solved itself for me) reminds me of the old softmod (no modchip) hacked first gen xbox .. If you left it without power for a while so the system clock was reset, there was some timing conflict between the network driver and the "jailbreak" .. putting it into a boot loop .. that after a while worked it self out. It could take 10-20 minutes and hundreds of reboots sometimes. The likelihood of this being related is of course slim to none - but since my xbox back then was basically only used for XBMC, just like my ATVs are today .. it still "feels" related

Anyway, might be worth trying. Hope it helps.

Hi everybody, thanks fpr the many tips. I finally gave up trying to install 4.2.1 via tiny umbrella and updated officially to the recent iOS 5.1 version. Apple TV works fine again, although no jailbreak and no XBMC, of corse. I will try to downgrade it on the weekend, it has cost me too many nerves to try to do that after work.

I'll keep you posted. Too bad that there is no real solution to this "No signal" problem except rejailbreaking.
What really dazzles me is that ATV2 and XBMC has been workin just fine for almost a year now, and the problem occured without any change of the setup from my side.


Thanks!
Tim