I was trying to resolve an issue with our LTE pack on Omnia. mmcli -m 0 said no SIM card is inserted, but I was sure it is there, I’ve even cleaned the contacts.
After a longish struggle, I found out that the SIM adapter we used could not hold the already cut-out nanoSIM properly. It was slightly popping up from the adapter when inserted into the SIM slot in Omnia.
To resolve this issue, I’ve cut a little piece of the thermal transfer gum supplied with the LTE kit and I’ve put it between the SIM card and the LTE modem. It seems to have the proper thickness to resolve this issue. When I screwed the LTE modem back, I felt like a 0.1 mm of the gum was pressed against the SIM using force. But I guess this is okay given the fact that the LTE card bottom side is just an EMI shield or heat transfer plate.
I haven’t read anywhere about this, only a vague mention here: LTE Quectel EC25-E - přestává fungovat, pomůže jen vyndání karty a SIM - #9 by lampra . So I’m sharing my experience.
If this shows to be a wider problem, it might be good to include at least some 3D printed part with the LTE kit, or to adjust the manual to say you should use a part of the gum to hold the SIM.