Bangle GPS Power management

More experimentation tonight. I can confirm that the UBX_CFG_2MIN() function will get an ACK response from the GPS. However thats not enough as the GPS still sends a fix every 1-2 seconds. The rate appears to be controlled by UBX_CFG_RATE(). So I tried the function below.

// header    class  id
// 0xB5 0x62 0x06   0x08

function UBX_CFG_RATE() {
  writeGPScmd([0x06,0x08,  // class, id 
         0x06,             // length
         0x00, 0x20,       // b0: 8192ms ie 0x2000,  0x00FF (~65sec)
         0x01, 0x00,       // b2: 
         0x01, 0x00]);     // b4: timeref GPS
}

This gets neither an ACK or a NACK so I assume that the GPS does not like the format or checksum and is ignoring it.

I found the following python code at:
[https://community.emlid.com/t/change-sam­pling-frequency-of-gps/421/2]

def ubx_change_rate(self):
      msg = [0xb5, 0x62, 0x06, 0x08, 0x06, 0x00, 0x64, 0x00, 0x01, 0x00, 0x01, 0x00, 0x7A, 0x12]
      self.bus.xfer2(msg)

But when I look at the bytes it does not match the datasheet.
But I tried it anyway, stripping out the sync bytes and CRC, but that did not get a response.