[Q] Custom ROM via Fake Sign? - G3 Q&A, Help & Troubleshooting

An idea occurred to me earlier today when checking to see if we had an unlocked boot loader for our G3s. Wouldn't it be possible to do something along the lines of signing our custom ROMs with the signature of the stock ROM? So that when the boot loader checks the ROM, it thinks its the stock version? I looked into it a little bit while on break at work and one of the HTC phones that had a locked boot loader did something similar to this (tricking the boot loader into thinking its stock). Unless there's other ways the boot loader checks for legitimacy, it should work. Granted if we did this we still wouldn't be able to do things like flashing kernels or making proper backups (or easy flashing in case of a bootloop!). Anyone have any other thoughts on it or know if we've tried it already? Most likely not due to no publicly available ROMs for the g3.
Tl;Dr Sign a custom ROM with the stock ROMs signature to use the custom ROM, even with a locked boot loader.
Sent from LGLS990

Try it fir yourself and let us know the result ?

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[Q] kernel flash question for the R800x

so i know its a noob question but so lets say you unlock the bootloader and you flash a kernel and boot the phone fully right, well what would happen if while your running a custom kernel and re-lock the bootloader what will happen to the phones state?????
i only ask this because it randomly poped into my head....
Never done it myself, but I'd imagine nothing special happens. You just can't change the kernel to a different custom one again, but you could flash over it with a stock FTF still
well i was just wondering becase it came across my mind so i thought i would state my thoughts

Flashing woes

Let me start by saying I'm fairly well versed in fastboot, adb, flashing imgs, recoveries, ROM's, etc... But I have never had issues like I've had trying to flash custom ROMs on this phone. Right now, I have the bootloader unlocked, TWRP 3.0.0.1 installed and stock-root.
What is the proper procedure to flashing a ROM such as Chroma? Some ROMs list having to flash the bootloader and radio in fastboot; some don't. Most of the ROM's don't mention anything regarding flashing vendor.img, which after much reading seems to be an essential step after flashing a ROM. Then there is a universal vendor.zip which I have no idea what it does. I'm just trying to get everything straight so I don't have to restore the factory imgs 4 more times like I have done in the past day trying to get a custom ROM to work correctly.
Any insight is appreciated.
JJHunterx said:
Let me start by saying I'm fairly well versed in fastboot, adb, flashing imgs, recoveries, ROM's, etc... But I have never had issues like I've had trying to flash custom ROMs on this phone. Right now, I have the bootloader unlocked, TWRP 3.0.0.1 installed and stock-root.
What is the proper procedure to flashing a ROM such as Chroma? Some ROMs list having to flash the bootloader and radio in fastboot; some don't. Most of the ROM's don't mention anything regarding flashing vendor.img, which after much reading seems to be an essential step after flashing a ROM. Then there is a universal vendor.zip which I have no idea what it does. I'm just trying to get everything straight so I don't have to restore the factory imgs 4 more times like I have done in the past day trying to get a custom ROM to work correctly.
Any insight is appreciated.
Click to expand...
Click to collapse
Bootloader and radio are not always updated every month. Your choosen rom dev should state if they have been when he releases an update. Alternativly you can decompress the factory images and see if they have been updated.
There is no requirment to update them. It has no ill effects if you leave them but I suggest to update them for ovbious reasons.
The vender image used depends on the google image the rom is based on. EG the latest google image is "J" so you need the vender "J" also. Again you can get these from the google images. These contain the hardware things your phone needs to run.
If you update the rom and a new vender is needed you will get an error on boot about a mismatch.
Again your choosen rom developer should supply or inform you if it is needed.
I use pure nexus, everytime there is an update my dev informs us if there is a need to a new vender or radio/bootloader and there are links in the thread to obtain these files.

S3 ATT Like to know how to unlock bootloader, root the phone, and install custom ROM

Hey first time posting on xda devs and would like to know how to unlock bootloader, root the phone, and install custom ROM.
Now I have spent entire day backing up and searching the different people root but if someone can help me and point me in the right direction that would be great.
So I have a S3 from ATT Model: SGH-I747, Version: 4.1.2 JellyBean, BaseBand Version: I747UCDMG2, Kernel: 3.0.31 - 1300972. It is a stock ROM, I have never done anything to the phone at all before.
Now I will admit I followed a youtube video call "How to Root AT&T Galaxy S3 SGH-I747!" by High on Android and I did everything in the video. I used odin v1.85, I did the PDA to the CWM.tar file, phone rebooted and I added the CWM superuser file and that is when I tried to get to CWM recovery mode and all I got was the phone's default recovery mode and not the CWM one.
From what I understand I believe I need to unlock bootloader first, but again this is a my first doing this and I hoping someone can point me in the right direction. Forum post state that you should follow guides that is exactly the same to the phone you would like to install custom ROMs.
Honestly I would like to ultimately be able to install a recovery mode that works with my phone that I am able to create snapshot image of my stock phone in case anything happens or I would like to go back to my stock image (which I highly doubt if everything goes fine) and install a custom ROM (I know there are different ROMs if someone can point me to where I can check out all the custom ROMs and not necessarily install those custom ROMs that would be awesome) and finally get rid of ATT loading screen when booting up the phone and install a custom boot loading screen, but of course I care more about getting the custom ROM install first.
If anyone can help that would be great.
The bootloader is not locked and using any app or program to unlock the bootloader will probably brick the phone.
The phones bootloader is already unlocked. Only verision s3 has a locked bootloader. Also you need to be in download mode for odin to work

Questions about the new bootloader

So I think many people here know about the new xperia bootloader that allows the use of normal roms ans recoveries with dedicated partitions (more details here http://forum.xda-developers.com/showthread.php?t=3096835).
But I also heard that upgrading to this bootloader made flashing stock ROMs impossible, so I wanted to know if that was true.
If true, I have a backup of my actual unlocked bootloader (didn't make a backup before unlocking because the warranty is loooong gone now) and if I restore it after making the update, will that allow me to go back to stock ROMs ?
Really hope I could get an answer, has anyone tried flashing stock ROMs after updating the bootloader ?

Anyway to change Boot Screen?

I would like to change the bootscreen to something else like play the game "Mario" or change it to something cool? I know past Android phones from older Android versions I was able to do that after I unlocked bootloader and achieved root. Though I'm having difficulties doing it on my moto g fast (boost mobile)
On another note I'm also having trouble flashing custom roms, I end up in a boot loop and end up having to flash the stock firmware back onto the phone to get it back up and running. I Have Twrp recovery and Magisk. I am rooted it says.

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