Although initially applied to upgrading the phone’s software, but in fact now many folks also utilize T-Mobile Galaxy S6 or Galaxy S6 Edge stock firmware to back to stock condition, recover a bricked phone or unroot. So, before performing procedures to obtain root, flashing recovery, flashing ROMs or any action that could potentially result in troubles, it’s a good idea to have at least one stock firmware that matches with your current phone software version or newer.
Each stock firmware is uniquely made based on the device model number, for example, you can’t use the T-Mobile Galaxy S6 stock firmware to AT&T branded S6 and vice versa. So, using the firmware that does not comply with your mobile device will lead you in big trouble. For that reason, determine your phone model number, just head to the main Settings> About device> Model Number.
As we said earlier, you can use a stock firmware for recovery purpose, by using a same firmware version with your device’s current software version, you can also use it to upgrade the firmware to flash the newer version, so you do not need to update it via OTA.
T-Mobile Galaxy S6 and S6 Edge Stock Firmware
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Downgrading sometimes works, but you might get several problems, since there are some parts of the firmware that can’t be downgraded after you upgrade it.