How to determine cause of boot halt in Samsung logo screen?

Question

The apps kept crashing on my phone (even MIUI Home) so I shut it down using the long power press and selecting shut down/power off option.

When I powered it back on, it just stays stuck on the Samsung logo boot screen with the yellow warning sign (which has been there ever since I rooted it).

Here's what I tried which didn't work:

• List item
• cleared cache, dalvik, fixed permissions - FAIL
• with above, it means booting into CWM works fine but booting into OS fails
• reflashed with MIUI i9100 ICS 2.12.14 (still downloading 3.1.25 as I type this) - FAIL
• removed micro SD and SIM and tried booting - FAIL
• earlier today, it started doing the crashing thing too but after reboot, it went into Safe mode. I rebooted again to get out of safe mode. After booting back normally into OS, all my non-system apps were out of there arranged folders and just listed in the next home screens like they were all reinstalled.

So I got to backing up my data with CWM and did a data wipe and it now boots successfully.

I need to restore my data. Can't work with a fresh wipe.

With this, at least I know it's not a HW problem. Or is it? :O

Answer 1

First of all, it always a good thing to have USB Debugging on. It can help you check your phone and even recover it if something is wrong.

When your phone is on a boot loop and won't start correctly, you can use adb to check where might be the problem. Connect your phone via the USB cable to a PC with adb and then type the following:

adb logcat

Power your phone and you should see, as your phone starts the boot secuence, a lot of information in the adb window. That is the current log of your phone boot secuence (like the one you can see in linux for example). If the phone ends in a boot loop, you should be able to see what is trying to do and then try to fix it.