CLK short circuit to GND BG95 M3

We prototype with a BG95 M3 module and have problems with a short circuit of the USIM_CLK line. We unsoldered the capacitor and cut open the connection to the SIM card holder to make sure none of these components are the reason for the failure.

I believe because of the short circuit the AT-Commands regarding the APP work fine (for example QPOWD command) but the commands regarding SIM connection (like CMGF, CMGL or CMGD) result in an ERROR - is this assumption right?

Is there any software reason why the CLK line is pulled down to GND - if yes how can I redo this pulldown?
I did a mistake in the layout by connecting the USIM_VDD with a 100nF capacitor to general GND and not to USIM_GND - could this somehow caused the CLK line short circuit?

This failure is on two PCBs out of an order of 5 PCBs so maybe it is an assembly mistake but I want to exclude any reasons. The other PCBs work fine with a resistance of around 55 k Ohm between CLK line and GND does that sound about right?

Thank you very much for any comments and advises to prevent this failure.
Bye Lukas

The ERROR answers from the module and the cut of the CLK line to the SIM card holder

You can use the command of AT+CPIN? to judgement the SIM card can be identified.
And according to the schematic ,it is recommended to add ESD protect devices for USIM circuits and pull-up resistor for USIM_DATA to prevent interference.
If the USIM_GND is connected to GND ,it is OK to connect GND to USIM_VDD.

You can refer to above.