EM12-G unsuccessful firmware

Hello, the modem was with firmware EM12GPAR01A21M4G and there were problems with Internet propagation after 5 minutes, while the modem connected to the network. It was decided to roll back the firmware to version EM12GPAR01A19M4G_01.001.01.001, the firmware was completed successfully. After restarting the modem, it ceased to be observed in the system. Current consumption is approximately 10 mA. How can it be restored? How to enable USB_BOOT mode?