I added a little bit of code to calculate proper checksum instead of hard-coding it. There's no checking for Firmware version. But otherwise it is pretty fool proof. It doesn't hurt to hit the fix button again. In fact it is encouraged to make sure it took off the ASK Bit.
It is very fast as it is only writing two bytes.
SendSbep(new byte[] { 0xF5, 0x17, 0x00, 0x02, 0x82, askByte });
SendSbep(new byte[] { 0xF5, 0x17, 0x00, 0x02, 0x89, checkSum });