[Replicant] Trying to reflash Samsung Galazy Tab A6, but encountered "FRP lock".

[A. F. Cano]

On Mon, Jul 12, 2021 at 01:22:05PM +0200, Denis 'GNUtoo' Carikli wrote:
> On Sun, 11 Jul 2021 21:36:08 -0400
> "A. F. Cano" <afc54 at comcast.net> wrote:
> 
> > Hi,
> Hi,
> 
> > At some point, I don't recall where, this device (Samsung Galaxy Tab
> > A6) was identified at i9100, but now that I've done a factory reset
> > lsusb only says:
> > 
> > Samsung Electronics Co., Ltd Galaxy series, misc. (MTP mode)
> How did you manage to identify it as "i9100" ? Sometimes things like
> lsusb and so on misidentify devices. It could be interesting as we
> might need to update our installation manual if there are some
> misleading clues somewhere.

I can't confirm it now.  After the factory reset the device is
completely useless.  It insists on a wifi connection first, and the
first thing it requires after that is a google account.  After I
entered the valid google account associated with the device before it
was factory reset, it keeps failing: "something went wrong" and
it goes back to ask the login Id and password.  I'll have to try again
from the original wifi network where the account was created.  I
wouldn't be surpeised if google uses all kinds of factors such as
comparing where the device is.  But this will take some time.  I'll
report back with details when/if I can get it back to a normal state.

> While we do support the GT-I9100 variant of the Galaxy SII, we don't
> support any Galaxy Tab A6 yet nor any Galaxy Tab A and as far as I know,
> no one tried to add support for any of the Galaxy Tab A in Replicant.
> 
> In most cases, installing a Replicant release for one device on another
> can be dangerous and won't work.
> 
> There are some exceptions though: when the devices are really close it
> sometimes work (though I don't know if it's dangerous or not).
> 
> For instance, I've managed to use the Galaxy Tab 2 WiFi (GT-P3110)
> images on the Galaxy Tab 2 GSM (GT-P3100). There also might be some
> devices that have 0 hardware differences but have different variant
> code names for one reason or another.
> 
> But here the Galaxy Tab A6 seems to have an Exynos 7870[1] or other
> processors/system-on-a-chip from similar generations so it looks very
> different. 
> 
> The Galaxy SII (GT-I9100) has been released in 2011, and I bet that the
> Galaxy Tab A6 is much more recent, so it's unlikely to contain the same
> chips.

This tablet had a date of 2014 some place, and is running android 5.1.
All this from memory since I can't access anything now.

> > I've managed to put it into Download mode, retrieved the pit file and
> > attempted to reflash the RECOVERY partition and the BOOT partition
> > with heimdall but it fails with this message on the device:
> > 
> > "Custom binary blocked by FRP lock"
> I don't know anything about FRP lock. Maybe LineageOS, xda-developers
> or postmarketOS have information on it. I would be interested to learn
> about it too, so if anybody has good links on it it would be great.

I'll check.  All the tools described anywhere I could find related to
the FRP lock were windows tools and I don't run windows at all.

> > I've searched and found various ways that supposedly allow this block
> > to be removed, but none work.  
> > 
> > The recovery.img (twrp) is supposedly for this exact device, the
> > boot.img allows for rooting it, but I can install neither.
> > 
> > This page:
> > 
> > https://www.droidviews.com/root-samsung-galaxy-tab-a-sm-t280-and-install-twrp/
> > 
> > has the instructions I followed and the images I downloaded.
> > 
> > Is there a way to bypass this "FRP lock"? There appears to be no way
> > to do anything on this device without a google account, or without an
> > internet connection.
> What is the exact variant code name of your device? SM-T280? 

This page describes exactly, as far as I could tell, the actual device.

> Is SM-T280 a variant of the Galaxy Tab A6?

Apparently.

I'll try to get it back to working order and report back.  Who knows
what I'll have to do.  Maybe run through hoops using the google account
to get it back to a normal state, and who knows if removing the FRP lock
is at all possible.

Augustine