I had this sort of problem and it was very embarrassing because as a so called IT professional because I did not have a full backup. However I used UFS Explorer and recovered everything - you need a 4 port SATA adapter and somewhere to put the data. It did take a while.
The problem was caused by a bad drive and the NAS was not great at report which one it was.
I would start with one drive and make sure you can load the firmware and keep the unit running. It could be you have a hardware problem with the box.
Getting the unit into EM mode can be tricky - are you following the instructions carefully? I found it tricky to change the default IP address. Also I had to use an earlier version of code that was previously running when I kept getting the blue light.
I have 2 X LS-QL83D : one runs V1.11 and the other has to have V1.10.
Boot imageshttp://newsandguides.com/how-to-downloa ... -software/http://buffalo.jp/support_ap/support/pr ... s_qvl.html
I have been facing the problem with my LS-QVL/E-EU for last 6 months. I was not able to access the NAS through the network. I tried multiple ways to reinstall/update the latest firmware (ls_series-171) without any success. NAS showed up while keeping only 1 hard drive on the unit and tried to install firmware with debug mode which failed all time.
Finally, I took out all 4 hard drives (4TB each) and formatted (of course I lost all the data since I did not have the backup) with CMD > dispart ..... > clean. method as suggested on the buffalo manual. Put back into the unit. But still the blue light is keep blinking and the unit starts frequently.
Unit worked well for almost two years since 2013 with 4 hard drives (total 16 TB). I don't know what happened all of sudden. I am not technically expert but can follow step-by-step instruction to resolve the problem.
Any help would be greatly appreciated.