LS751 authorisation error #9] at boot

Caught in dreaded boot loop (yay LG!). Recovery logs indicate /dev/tty0: no such file system or directory found. Only option is SD card: can i install patch and where to find it? Going for broke: can i install ROM that way? The IMEI/ SN display screen comes up and i can access the recovery menu. Any advice is welcome and thanks in advance!

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