[Nexus 4 Q&A, Help & Troubleshooting] lesensei:
Hello all,

This is yet another bootloop story, although I haven't found anything quite like it yet, hence the idea to post it here for reference and in case some of you have interesting ideas to explore...

This is gonna be a bit long, but TL;DR: After my phone got "spontaneously" stuck into a bootloop, I find that only the stock 4.2.2 rom works, and no other.

So, tuesday I get back home with an empty battery and a Nexus 4 (running latest OTA) that has switched itself of after a day of somehow intense usage. No worries, I plug the AC adapter, let it charge for a bit and switch it back on. Booting seems a bit long, but I have to take care of a few home chores so I let it do its thing before coming back to it a few hours later. Only to find it still displaying the animated nexus logo. After a few switch off/switch on cycles, I understand its pretty stuck and I need to be more radical about it. So I enter the bootloader menu, and OEM unlock the phone (I had never needed to do that) hoping the full wipe associated with that will clear things up.

Well, it didn't. So I guess I'll need to flash a stock rom, and so I do. Since 4.4 is available on Google's stock roms page I try that, the animated logo changes but the end result is the same. So I try again with the latest JB (4.3) and still the same result. I get more than a bit frustrated but it's late and I need some sleep.

The next day, I call Google's warranty desk in France. They tell me that since the phone fell a few month ago, they cannot take it under the warranty program, and so I have to ask LG. Knowing there's no reasoning that will get me past the clerk that answered the phone I hang up after saying I'll get back to them via snail mail. Which I'll probably do soon, because I'm very disappointed with the way that warranty desk works.

Once at work, everytime I have a few spare minutes, I try to reflash with a new tool just in case it does more than automate what I did manually (nexus root toolkit being the one I tried most). It doesn't change a thing and my phone is still a nice animated paperweight.

I don't know why I ended up trying that, but I finally tried flashing the original 4.2.2 rom, and lo and behold, my phone finally got to the SIM code screen ! Everything worked nice after that, so once back at home, I go for the offered OTA upgrade to 4.3. Well, guess what, back to paperweight. Before reflashing 4.2.2, I took the time to flash CWM and activate adb by modifying /system/build.prop in the 4.3 image. This showed a recurrent problem with "system_server" segfaulting at launch (and it might have been caused by hal_sensors_get_list not returning anything, I have no clue). Trying the same on 4.4 yielded the same result.

Back to 4.2.2 and everything works fine, but I get nagged by the OTA notification, and more than that I'm wondering if there's any hope I might understand and fix the problem with my phone.

So, ladies and gentlemen, any clue that would help me is very welcome !

I plan to try a CM rom this week-end to see if it has the same problems as the stock one, but I have little confidence it doesn't. My guess is I have a hardware problem that's non-critical except it triggers a bug in 4.3+...

Thanks for reading !

--

Alain Perry