V-Core 3 - Octopus 1.1 and RPi connection issue - 'mcu': Unable to connect

After first bed mesh probing with Beacon H the printer stopped responding. Klipper returns the error: "mcu 'mcu': Unable to connect". Reinstallation from scratch (new images for the Pi and the board)didn't help. It seems RPi works fine, but it still cannot connect to the board. Tried flashing with RPi and PC via DFU, none of them worked. Under USB devices the unknown one shows, similar to yours, but I don't see DFU connection. Can I check something else or is the bard fired?