DS-412+: blinking orange status light, blinking blue power light

I have a DS-412+ which went off-line, the status light is blinking orange, the power light is blinking blue. Based on the manual, this means the volume is degraded, crashed or that there is no volume. The thing is, the behavior doesn't change if I remove the drives or remove them and add in a completely new drive.

Does anyone know what it could be? I'm guessing a faulty power adapter? Perhaps something with the drive controller?

I'll probably buy a new 4 unit NAS regardless (the 412+ is pretty old), but I'm thinking of finding another PSU and trying it out, thoughts?