WD MyCloud Home Duo lost all files

Hi, I changed my two old HDD to newer ones. After starting Home Duo the LED flashes fast, I tried

  1. 1-29sec reset.
  2. 30.50sec reset
  3. 40sec reset and
  4. 50-60sec factory hard reset. I tried all options for 5 hours but nothing worked. So I switched to the old ones but nothing, still flashing. Suddenly after a short reset and 25min waiting the Home Duo is working again but I lost 2TB files. Is there an easy (mabye free) tool to recover all my files?

There is a good example here, using another NAS (not Western Digital) to recover data from the MCH. This can also be done with most PCs that could boot a free Linux data recovery ISO, such an example is mentioned in this link below.