C# BinaryReader and Little Endian

I have to read a binary file so I use this code:

static void ReadBin()
        {
            var sectors = new List<Sector>();
            using (var b = new BinaryReader(File.Open("C:\\LOG.BIN", FileMode.Open)))
            {
                const int offset = 4096;
                const int required = 2;
                int pos = 0;
                var length = (int)b.BaseStream.Length;
                while (pos < length)
                {
                    for (int i = 1; i <= 640; i++)
                    {
                        pos = (offset*i)-2;
                        b.BaseStream.Seek(pos, SeekOrigin.Begin);
                        // Read the next 2 bytes.
                        byte[] by = b.ReadBytes(required);
                        sectors.Add(new Sector { Number = i, Position = pos, Type = Sector.SetTypeFromExadecimalString(ByteArrayToString(@by)) });
                        pos = pos + 2;
                    }
                }
            }
        }

As you can see the ByteArrayToString take the array of byte and write a string. The code of ByteArrayToString is:

    public static string ByteArrayToString(byte[] ba)
    {
        StringBuilder hex = new StringBuilder(ba.Length * 2);
        foreach (byte b in ba)
            hex.AppendFormat("{0:x2}", b);
        return string.Format("0x{0}", hex.ToString().ToUpper());
    }

The machine that write the .bin file write it in LittleEndian. So following this StackOverflow thread "Is .NET BinaryReader always little-endian, even on big-endian systems?" I should be in "all" LittleEndian format (the ReadBytes and also the file generated by the machine). The problem is that the function ByteArrayToString() gives me this result: 0xF0FF that is in BigEndian and not in LittleEndian (infact I suppose that I should receive instead 0xFFF0), because after that I have to decode a lot of data and I can't be sure of the consistency of result (I have nothing to compare), I don't want to have problem to decode the .bin file, how can I achieve to obtaing 0xFFF0?