I have recently opened my 236 unit to reset it and took some pictures for those who are interested.
Why? After synchronizing protocol and baud rate through the SiRFDemo utility my 236 would only send unrecognizable byte sequences over the Bluetooth connection. There was no way of resetting the protocol or baud rate with any software. I verified the raw output format was not in the Sirf binary protocol as some posts in this forum suggested.
The most likely reason for this behavior was that the sync feature had set the Sirf chipset to a baud rate that exceeded the 236′s builtin Bluetooth radio’s capabilities. In this situation a software reset is probably only possible via a separately sold special USB cable. (A standard USB cable will not work).
Living in a place where obtaining such a cable would incur higher costs and a longer waiting time, I had to find another way to reset the unit.
After failed attempts to cause a reset by running down the internal buffer battery for several days (removed big battery), the best solution seemed to open the unit and physically reset the internal ram.
The biggest challenge was to find a way to open the case. After some trial and error (need strong finger nails), the unit opened from the side of the USB connector. You should be able to get a better understanding of the connecting mechanism from the pictures below.
Originally my intention was to unsolder one of the backup battery pins to reset the 236. However there is a faster way: the battery pins are very close together and after causing a short-circuit by connecting both pins for a fraction of a second, the unit was already reset! Although it would be preferable to cause a voltage loss by unsoldering the battery, causing a quick short-circuit should not damage the battery.
Hope the pictures are helpful to anybody in the same situation.
Remember: Never use the “Synchronize Protocol & Baud Rate” menu option in SiRFDemo with the 236 connected via Bluetooth.
For more pictures, see my original post in this forum.