[tutorial] reset unlocked bootloader FC flash counter

[DrWowe]

In the spirit of the old TriangleAway here is how you can make the "FC N" disappear from your unlocked bootloader screen. The N is a number that gets bumped every time you "fastboot flash". This method requires a root shell, if you have busybox installed (e.g. from the Magisk module) it can done 100% on phone. Could help you out if you ever need warrantee service, or just don't like seeing the bootloader count how many times you've messed with the phone.

OnePlus7TProNR:/sdcard # dd if=/dev/block/by-name/param of=param.dd
2048+0 records in
2048+0 records out
1048576 bytes (1.0 M) copied, 0.017794 s, 56 M/s
# xxd -g 1 param.dd > param.xxd

Now use an editor (vim, nano, whatever) to look for this line in the file:

00003420: 00 00 00 00 01 00 00 00 01 00 00 00 17 00 00 00  ................

The flash counter is stored in the first non-zero bytes. Change them to zero like this:

00003420: 00 00 00 00 00 00 00 00 01 00 00 00 17 00 00 00  ................

Finally, flash the partition back, and voila, the "FC" line is gone from the bootloader. Note, these steps would have to be repeated every time you fastboot flash something.

OnePlus7TProNR:/sdcard # dd if=/dev/block/by-name/param of=param.dd
2048+0 records in
2048+0 records out
1048576 bytes (1.0 M) copied, 0.017794 s, 56 M/s
# xxd -r param.xxd > param-0.dd
# dd if=param-0.dd of=/dev/block/by-name/param

 

[lendawg]

Wait....so does this get rid of the unlocked bootloader screen altogether?

 

[DrWowe]

Wait....so does this get rid of the unlocked bootloader screen altogether?

No. Once you've used a "fastboot flash" command, you'll see a line on the bootloader/fastboot screen that says "FC 1".
If you fastboot flash something else, it increases to "FC 2" and so on. I think it persists even if you re-lock the bootloader as an indicator to the manufacturer and carrier that you've messed with your phone, and how many times.

This technique will make that counter go away, making it easier to re-lock the bootloader and make the phone appear unmodified, in case you ever need warrantee service.

 

[DrWowe]

There used to be a tool called "Triangle Away" that did something similar a few years ago, but it isn't supported anymore. But this technique does the same thing, you can read more about it here:
https://forum.xda-developers.com/galaxy-s2/orig-development/2014-01-15-triangleaway-v3-26-t1494114

 

[ohap]

This is just to remove the counter . Any warranty work will probably still be denied seeing you phone is on record as unlocked bootloader when you submit for the unlock.bin. And I'm sure the well I got the unlock.bin but never used it line will not work lol