Glad you got it all sorted. You've only missed one other poo-trap which is not explained elsewhere...
If using this speedo with a 1S pack, always set the voltage protection to 'Non-protection' from the PC when downloading software updates to the speedo. If you don't, then when you plug in the 1S cell, the green LED blinks and nothing happens. For reasons that surpass understanding, if you set the voltage protection to anything else (even 3v) the speedo expects to get at least 7.4v and throws its teddies out of the case! If you choose 'Non-protection' is seems to work fine.
The answer is always to use a 2S pack for software updates, to reset to your radio, and to set the voltage protection separately from the 2-in-1 box to what you want before you race. If that is done, all goes well. Hope you like the speedo as much as I do - really good kit at a great price. HTH
