Problem updating galaxy s2 firmware
Samsung Galaxy devices feature a Download Mode that prepares your device to receive data from your computer via a dedicated flashing tool called Odin.
Here’s how you can boot your Samsung phone or tablet into the Download Mode.
Please note that a correct firmware is one that matches your device model and the country/region from where you purchased and using it.
To do so, find out your device model by going to Settings If your phone is not SIM-locked or carrier-branded, you can install any unbranded firmware that matches your device model regardless of CSC match.
As you know that there are several Odin versions available but considering the rate of success, you should use Odin3 v3.09 (for Jelly Bean and Kit Kat) or Odin3 v3.10.6 (for Lollipop).
Download Odin – Latest and All Versions Make sure to download the correct firmware for your Samsung Galaxy smartphone or tablet.
Turn off your device and then press and hold Volume Down Home Power buttons simultaneously for 2-3 seconds.
On the newer Samsung Galaxy flagships (like Galaxy S9/S9/Note 7) with no Home or center button, you need to hold the Volume Up Bixby Power keys.
Now download the recommended Odin tool for flashing the firmware on your Samsung device.
Suppose you are installing firmware and the battery juice drains away during the procedure, your phone or tablet might be hard-bricked.