Issued AT#USBCFG=0, now ttyUSB interface does not respond to AT commands

Cellular Modules
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1

I could read AT command responses on one of the ttyUSB interfaces, ttyUSB4.

// default value is 1
AT#USBCFG?
#USBCFG: 1

I changed it to 0 by issuing AT#USBCFG=0.

Module rebooted.

I can no longer issue AT command/ read response to AT command on ttyUSB interface.

Any way to achieve so now?

Using Telit FN980m cellular module, connected to Ubuntu machine.

2

I could access the modem interface through the AT controller on the Windows machine and could change #usbcfg back to 1. Now I can access the AT interface from Ubuntu OS.