RFD868 TXMOD don't bind, don't show version number

hi all,

i have some TXMODs 868mhz and some of the new RFD868ux. Never had a problem with either, apart one TXMOD unit, which i tried to upgrade to fw 3.15 (they come with 3.07 and will not comunicate with the UX coming with the 3.15. This unit don’t show version number, don’t show radio parameters “sorry, there’s no radio parameter to fetch” (??) and neither comunicate with any of the UX modules i have.
Do i have a defective one? or there’s a way to reset it? (i tried to upgrade fw a couple of times)

edit: i tried to flash the very last 3.16, txmod 1.4.1. seems to have same problems, apart in the modem version number now shows “RFD SiK”, with previous fw it was blank. No radio parameters come, either.