[Android Q&A, Help & Troubleshooting] Dino10or:
Hello there, as of late, I've been trying to exploit the Settings.APK on the HTC One M9 (specifically the verizon version, although the APKs are the same there is just a value on the device itself that is different which triggers the "block" on the APK), as you can see here:

http://xdaforums.com/verizon-one-m9/general/bypass-verizon-enable-oem-lock-t3281994#post64568917

I've discovered that it is possible to patch/overwrite the existing Settings.APK with adb install -r -d (overwrite and downgrade), even a modified one I've worked on with APKTools (without root). However, I've run into several issues, mainly modifying the java code and getting it to recompile (with the APK Multi-Tool I'm using to compile "system APK files) WITH the apk.

What I mean to say is that when I place the java code in /src it will compile but I don't see the changes taking effect.

EDIT: Now when I try to compile I get an error.

Building Apk
I: Using Apktool 2.0.1-825476-SNAPSHOT
I: Checking whether sources has changed...
I: Building java sources...
"An Error Occurred, Please Check The Log (option 26)"
Press any key to continue . . .

java version "1.8.0_66"
Java(TM) SE Runtime Environment (build 1.8.0_66-b17)
Java HotSpot(TM) 64-Bit Server VM (build 25.66-b17, mixed mode)
A subdirectory or file modified-system-apk-files-here already exists.
Exception in thread "main" java.lang.UnsupportedOperationException: Not yet implemented
at brut.androlib.java.AndrolibJava.build(AndrolibJava.java:32)
at brut.androlib.Androlib.buildSourcesJava(Androlib.java:390)
at brut.androlib.Androlib.buildSources(Androlib.java:299)
at brut.androlib.Androlib.build(Androlib.java:282)
at brut.androlib.Androlib.build(Androlib.java:256)
at brut.apktool.Main.cmdBuild(Main.java:225)
at brut.apktool.Main.main(Main.java:84)

EDIT EDIT: Apparently I need the smali code instead. I'm going to try to convert java to smali and hopes this works. Fingers crossed!

APKTools is having an issue decompiling the resources in the first place,

C:\Program Files (x86)\Minimal ADB and Fastboot\modified settings>java -jar apktool.jar d Settings.apk
I: Using Apktool 2.0.2 on Settings.apk
I: Loading resource table...
Exception in thread "main" brut.androlib.AndrolibException: Multiple resources: spec=0x7f100000 bool/config_allow_edit_carrier_enabled, config=[DEFAULT]
at brut.androlib.res.data.ResConfig.addResource(ResConfig.java:63)
at brut.androlib.res.data.ResConfig.addResource(ResConfig.java:56)
at brut.androlib.res.decoder.ARSCDecoder.readEntry(ARSCDecoder.java:223)
at brut.androlib.res.decoder.ARSCDecoder.readConfig(ARSCDecoder.java:191)
at brut.androlib.res.decoder.ARSCDecoder.readType(ARSCDecoder.java:159)
at brut.androlib.res.decoder.ARSCDecoder.readPackage(ARSCDecoder.java:116)
at brut.androlib.res.decoder.ARSCDecoder.readTable(ARSCDecoder.java:78)
at brut.androlib.res.decoder.ARSCDecoder.decode(ARSCDecoder.java:47)
at brut.androlib.res.AndrolibResources.getResPackagesFromApk(AndrolibResources.java:544)
at brut.androlib.res.AndrolibResources.loadMainPkg(AndrolibResources.java:63)
at brut.androlib.res.AndrolibResources.getResTable(AndrolibResources.java:55)
at brut.androlib.Androlib.getResTable(Androlib.java:65)
at brut.androlib.ApkDecoder.setTargetSdkVersion(ApkDecoder.java:197)
at brut.androlib.ApkDecoder.decode(ApkDecoder.java:96)
at brut.apktool.Main.cmdDecode(Main.java:165)
at brut.apktool.Main.main(Main.java:81)

which leaves me with a resources.arsc presumably containing many files I need. I've downloaded APKtoJava_RC2, and managed to decompile it into java code using that (and I'm not sure if the classes.dex matters), and modify the APK to where I can enable the OEM unlock feature, but I need to recompile it. I'm trying to recompile the thing, but I'm running into issues (I've tried putting the modified java in src and deleting the resources.arsc when compiling) when installing.

EDIT EDIT EDIT: I've just been trying to edit the SMALI code to let me access the OEM unlock, I guess it's going to be trial and error for me. :v

So, here's what I need to do, in all essentiality:

1. Decompile Settings.APK to the point where I can modify it.

2. Recompile Settings.APK with the same signature.

I'm not sure if this is possible (editing the java while keeping the same signature), but root is NOT an option.

If anyone is willing to give me some insight, I'd really appreciate it.