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[Q] Firmware question

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Bazooka Tooth
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(Last edited by Bazooka Tooth; 27th June 2014 at 05:40 PM.)
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Default [Q] Firmware question

Hey guys, I've currently got some wifi issues that I believe are firmware related, I've currently got 17.1.1.A.0.402 but would like to revert back to 17.1.A.2.36 ideally without having to factory reset my phone, I'm also not sure it would go back to 17.1.A.2.36 even if I reset it, I didn't note what firmware it had before I upgraded the firmware so it might take it back to an even earlier version ideally I just want to step back one firmware update but I'm not sure if this is possible? I noticed there's an option on PC companion to reinstall all the updates again although I don't know if you can choose which updates to install or whether it'd just install all the updates so far including 17.1.1.A.0.402 which would be no good. It also said I would lose all my phone data which is not ideal. I was considering rooting my phone and getting an older firmware installed then but tbh I don't really have a lot of knowledge on the subject and I'm not sure if that's even possible. If anyone could help help me out that would be great, even if it's to conform that factory resetting is the only option as ideally I don't want to lose all my data
 
ricebun
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If you're simply looking to root the device at the .402 firmware, then have a look at this thread. I personally did the same steps on my international D6503, and now have root access, my own TA backup file, PhilZ + TWRP recovery modes, and a locked bootloader. Originally my intent was to downgrade firmwares and us a root exploit that way, however, the 'EasyRoot' method has saved a lot of trouble and my firmware version has not needed to change at all.

That said, if you're still adamant about rolling back firmwares, I'd suggest that you have a look here. Norti has posted a fairly comprehensive set of instructions, as well as a list of firmwares for different versions of the Z2. Although I haven't rolled it back, I have heard that using flashtool to jump to different official firmware versions will not wipe data if you choose to not select WIPE USERDATA, since they're performed in a way that is similar to OTA updates (might need confirmation on this one). Some of the posters in that thread have claimed that as long as your device matches the firmware, loading up a different region's firmware shouldn't have any detrimental affects (i.e. an international phone using Taiwanese/German versions), but that's another piece of information I can't confirm since I haven't tried it.

TL;DR you don't have to change firmware to root, but you can if you really want to. Neither method should touch your SD card, and flashtool should be able to choose what should or should not be wiped.
 
Bazooka Tooth
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Default 1740

First of all thanks for the informative response! I tried resetting my phone anyway and it already had 402 installed at stock so unfortunately I can't do it that way, I think I'll try rooting my phone now as I've wanted to do it for a while and I might as well now seeing as I basically have a fresh phone with nothing installed on it. I think I'll follow this guide since I already have an unlocked bootloader: http://forum.xda-developers.com/showpost.php?p=53220418&postcount=2 However I was wondering when I can flash the older firmware, would it be during of after I've rooted my phone?
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