Hi I have just put together a TT build using second hand ultegra di2 parts except for R671 bar end shifters which are new, my RD is 6770 and FD is 6770, battery came from a 10 speed set up bmr-1, and front junction box is SM-EW67A, i didnt use SM-JC41 as ive soldered the cables internally and ive also soldered the r671 with the sm-ew67a, now my problem is the tt shifters dont seem to be cummunicating with the system, the sm-ew67a lights green when battery is connected and lights red when i hold button to put it in adjustment mode, also when i connect my road shifters 6770 to the system it works fine, my question is which component should i update the firmware? I gave the bike to my local bike mechanic and he said that the system doesnt recognise the shifters and that to disconnect right shifter but they are soldered and to avoid stripping cable again is there a solution?

any ideas?

thanks