If the machine is detected by the PC, then you can use a system upgrade utility to completely flash a new firmware. In some cases, the utility forces firmware writing in the NAND of the machine even if you have errors. It doesn't matter if it's not working as long as it's detected by PC. Use the Upgrade firmware package available on the official website. Download the version want (2.10 or 3.10) then unpack the archive. Start UpdateTool.exe and follow the procedure.
Warning: Read the note with the yellow background before proceeding to system flash.