Bafang have got back to me.
They are preparing stronger new software for the motor and sending me the BESST tool so I can install it via a laptop.
I’ll update the thread with progress.
Let me know if you have any questions with the BESST tool. I cut and paste some general directions from the Luna forum they should apply:
FLASHING FIRMWARE
Note 1: These instructions apply to circumstances as they existed in early January. I fumbled around a lot in the process and am not able to outline the exact steps that work immediately, but the info here should enable you to get the job done. Proceed at your own risk.
Note 2: “the right COM port” (the correct COM port) did not seem to be an issue in my case. Also, sorry for the (over)abundance of detail.
1. With X-1 battery installed in your bike, open the BESST application, select offline mode (if that option is not available, see steps 3 and 4 of “INSTALLING THE BESST APPLICATION,” above)
2. Connect the BESST tool (hereafter abbreviated BT) to a USB port of PC.
3. Connect the BT’s triangular green cable ends to the bike (unplug the cable that comes out of the bike’s display and leads into the frame, and patch the BT into that path).
4. Turn on bike’s power the usual way. Note that the display will probably light up on connection to the BT, but you still need to power the bike on at battery. Click “CONNECT” in the BESST app (abbreviated hereafter as ‘BA’).
5. Choose “update” from tools menu in BA (left side of screen), then in the next screen, click the “service tool” button. You have to click connect then "read" to get the BESST tool to read the S/N of your motor. It will not update until you get it to do this.
6. Click “Get a file from local” and navigate to choose the firmware file you want to apply.
7. Click the green oval “Update” button at bottom of screen and to upload the file into BT. This goes pretty quickly; when it’s loaded you’ll hear a single beep.
8. Unplug/replug the BT from/to the cable leading into frame to start the upload to bike; the app’s red progress bar should go (pretty quickly) up to 100%, then two beeps should sound.
9. To check the (hopefully new) firmware version, hit ‘Reset’ in upper right of screen, then ‘Connect,’ then ‘Read.’ (maybe ‘Clear,’ then ‘Read’ would do?). If you don't do this, the old FW version will continue to display, regardless of whether the FW updated successfully.