The only other thing you could try is to update the SARA's firmware to 05.12. See Firmware upgrade for UBLOX SARA-R410M-02B on the MKR NB 1500 #2
Honestly, if I were you I would abandon this board and use something else. The code has bugs, no documentation, and both U-Blox and Arduino support is useless. I've spent over a year wrestling with these boards and knowing what I know now, I wouldn't use them again.