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[Q] SIM Unlock, Downgrading 4.1.2, and Modified Status

OP YabosMcGee

11th January 2014, 11:55 PM   |  #1  
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So, I was given a T-Mobile SGH-T999 that someone had found a while back, but was unable to get activated. It didn't have a SIM in it, and I think it may even have been used off T-Mobile at some point (based on evidence below). Checking the IMEI it seems that it's only blocked on T-Mobile (AT&T says they do not have a block against this IMEI, and it's not showing up in any lost/stolen databases), so I'm guessing non-payment or carrier unlock. I would like to SIM unlock it, but I'm not entirely sure what has been done to this phone. I've never owned or played with a Galaxy S3, so my only knowledge has been from digging around this forum for a couple hours. Here's what I can tell you from looking through this phone. I'm hoping to get some advice on my next course of action:
  • Model number SGH-T999
  • Android Version 4.1.2
  • Baseband version T999UVDMD5
  • Kernel version 3.0.31-1128078 se.infra@SEP-128 #2 SMP PREEMPT Mon Apr 15 11:59:10 KST
  • Build number JZO54K.T999UVDMD5
  • Device Status Modified
  • Odin Mode
  • Product name SGH-T999
  • Custom Binary Download: Yes (1 counts)
  • Current Binary: Custom
  • System Status: Custom
  • Qualcomm Secureboot: Enable

I first tried SIM unlock, only to eventually find out that I would need to downgrade from 4.1.2 to 4.1.1. The threads I've read on downgrading indicate that to get back down to official 4.1.1 I need to be stock to begin with. I don't think this phone is rooted because I am unable to "su" when using adb shell or browse directories like /data. However, Odin saying it has a custom binary, and the device status saying modified makes me believe this phone was rooted at some point. Again, I have no experience with the GS3, so I may be way off base (I don't even know if Odin is the stock recovery).

So, before I can downgrade to 4.1.1 do I need to use Triangle Away, reset the flash counter, etc? Or, can I just use Odin to flash 4.1.1. Finally, will I also need to flash a different modem even after that?

I'd appreciate any advice and help you can give me. Thanks.
12th January 2014, 12:34 AM   |  #2  
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Thanks for doing some research before posting. Its refreshing to see you picked up basics even if you have never used this model before.

You didn't mention if there's a custom recovery such as TWRP or CWM. If it was there and you were brave or comfortable enough, I'd have suggested a 4.1.1 modem to flash (UVDLJC).

So to your question on unlock, essentially, your best bet is to flash a Root66 of UVDLJC version. Read the first post of Root66 completely word for word before you download and flash. Less chances of hard brick that way. A Root66 is a Galaxy S* family term for rooted stock firmware. It just has root injected in it. Everything else is just stock. So it does not trip the flash counter.

Now your counter is already tripped. So you will have to use Triangle away as you already know. So after Root66 and Triangle Away, you will be all stock and good to go. Follow the process for unlock as you have already found out and then go with ATT.

Now if you wish, after the unlock, you can flash UVDMD5 version of Root66 and you will get JB 4.2.1. Do not flash UVUEMJC version of Root66. Locked bootloader and efuse hardbrick lie in that direction.
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12th January 2014, 01:24 AM   |  #3  
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Quote:
Originally Posted by Perseus71

Thanks for doing some research before posting. Its refreshing to see you picked up basics even if you have never used this model before.

No problem. I work in IT, so I know the frustration of someone asking for help without even trying to do any basic research first

Quote:

You didn't mention if there's a custom recovery such as TWRP or CWM. If it was there and you were brave or comfortable enough, I'd have suggested a 4.1.1 modem to flash (UVDLJC).

Looks like I should have done my research a bit better. I misunderstood, thinking that Odin was some sort of recovery. Just looked up how to get into recovery, and it looks like stock to me (it just reads Android system recovery 3e). So, it is possible to just simply flash LJC modem on 4.1.2 so I can unlock, or am I misunderstanding?

Quote:

So to your question on unlock, essentially, your best bet is to flash a Root66 of UVDLJC version. Read the first post of Root66 completely word for word before you download and flash. Less chances of hard brick that way. A Root66 is a Galaxy S* family term for rooted stock firmware. It just has root injected in it. Everything else is just stock. So it does not trip the flash counter.

Now your counter is already tripped. So you will have to use Triangle away as you already know. So after Root66 and Triangle Away, you will be all stock and good to go. Follow the process for unlock as you have already found out and then go with ATT.

Just to make sure I understand correctly, it IS Triangle away first, then Route66 second? If I'm interpreting correctly, I can do this even if not rooted? All the devices I've ever flashed ROMs to before (even when going back to stock ROM) needed a custom recovery and/or root. But, since this device doesn't appear to be rooted, I just wanted to make sure I don't need to root before flashing Route66.

Quote:

Now if you wish, after the unlock, you can flash UVDMD5 version of Root66 and you will get JB 4.2.1. Do not flash UVUEMJC version of Root66. Locked bootloader and efuse hardbrick lie in that direction.

Thank you so much for the information. Once I get everything in order, and the SIM unlocked, I'll probably spend many hours researching how I want to progress (so you've already helped cut down that time). I honestly haven't come across modem flashing in previous devices, so I will definitely need to read more to fully understand the implications.

Out of curiosity, do you have any theories on how the flash counter was tripped? Everything appears to be stock, but the flash counter and device status seem to indicate otherwise. Just trying to figure out the history of this device. Again, thanks so much for the help.
Last edited by YabosMcGee; 12th January 2014 at 04:23 AM. Reason: Formatting
12th January 2014, 07:52 AM   |  #4  
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Really everything Perseus said is on point, except you don't need to use triangle away because really that's just to reset the counter and its unnecessary for you.. You can either flash a custom recovery and flash the LJA or LJC modem to do the unlock, or Odin the LJA or LJC firmware and proceed with the unlock

Edit: and to answer how the counter was tripped, it looks like they may have rooted it at some point and then unrooted it and returned it to stock.. The counter does not change

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Last edited by serio22; 12th January 2014 at 07:56 AM.
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12th January 2014, 05:47 PM   |  #5  
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Quote:
Originally Posted by YabosMcGee

Looks like I should have done my research a bit better. I misunderstood, thinking that Odin was some sort of recovery. Just looked up how to get into recovery, and it looks like stock to me (it just reads Android system recovery 3e). So, it is possible to just simply flash LJC modem on 4.1.2 so I can unlock, or am I misunderstanding?

Just to make sure I understand correctly, it IS Triangle away first, then Route66 second? If I'm interpreting correctly, I can do this even if not rooted? All the devices I've ever flashed ROMs to before (even when going back to stock ROM) needed a custom recovery and/or root. But, since this device doesn't appear to be rooted, I just wanted to make sure I don't need to root before flashing Route66.

Yes that's stock recovery. You can't flash modems with it. If you have custom recovery then the flash counter will keep on tripping at every boot. Best if use ODIN to flash LJA or LJC firmware, do the unlock and then flash MD5 firmware so you are back to JB 4.2.1. Triangle Away's purpose is to reset that flash counter you saw. I do believe it needs Root. I don't remember since I did it so long ago. I just thought you will want to it after all this flashing is done so its all squeaky clean.

Quote:
Originally Posted by YabosMcGee

Thank you so much for the information. Once I get everything in order, and the SIM unlocked, I'll probably spend many hours researching how I want to progress (so you've already helped cut down that time). I honestly haven't come across modem flashing in previous devices, so I will definitely need to read more to fully understand the implications.

Theoretically with android architecture, it could be done on any device. The trick lies in remounting that partition as read-write correctly. Have fun reading this.

Quote:
Originally Posted by YabosMcGee

Out of curiosity, do you have any theories on how the flash counter was tripped? Everything appears to be stock, but the flash counter and device status seem to indicate otherwise. Just trying to figure out the history of this device. Again, thanks so much for the help.

Looks like Serio beat me to it. He's spot on where the origins of the tripped counter is concerned.
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12th January 2014, 08:36 PM   |  #6  
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Thanks Persus77 and serio22. Everything worked out great.
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