Try the following (Boot 3 worked for me)
Emergency boot modes
Four emergency boot modes are supported:
Mode 1 (LED white, slow blinking ). Starting STB from the first (main) bootloader - if a second copy of the bootloader was installed in the STB, this mode switches the STB to start from the first (installed in the factory) bootloader;
Mode 2 (LED white, quick blinking). Selecting alternative NAND - if for some reason the download or update of the software from the current memory bank has not been successful, this mode switches the loading from the alternative flash memory bank;
Mode 3 (LED red, fast blinking). Reset to factory settings - if some STB settings do not allow to boot, you may need to reset the environment variables of the STB software to the initial value;
Mode 4 (LED red, lit constantly). Emergency startup - loading the System Recovery Utility menu via USB or over the network (requesting update data via DHCP protocol) - in some cases, if you can not boot from modes 1-3, this mode is used.