Totally bricked PR4100 - drive LEDs blinking red?


My PR4100 has been working fine for two years, but in the early hours of August 25th it disappeared from the local network.

Looking at the device itself, no disks are spinning and the only signs of life at all are the drive activity LEDs, which are ominously blinking red in sync with each other. The power LED and the display are off.

No amount of off-and-on-again or 4/40 second resets are having any effect. I’ve tested the power brick and it’s putting out the proper requirements, so the problem doesn’t lie there.

WD Support have said that as my 2 year warranty expired two months ago, they’re not interested in helping me out.

So, anyone here have any ideas?


Depending on the source of your problem, recovery might be possible. It all depends on whether or not you have a hardware problem. If it’s a firmware problem, the following guides should be helpful.

Generally, it’s a good idea to start by removing all hard drives, marking which bay they were installed in. Hard drives are not needed for firmware recovery, and it eiminates the possibility of accidental data loss.

It’s likely that you may be unable to access the rescue firmware files stored on your NAS. In that case, they can be downloaded from the link below.


Many thanks for your reply,

I’ve already followed your USB boot guide (much appreciated, you documenting all of this stuff for the community) although I was in a hurry at the time and only had a Mac to hand, so I formatted the stick as exFAT with an MBR partition scheme - with no joy, the system didn’t respond in any different way at all (flashing red drive LEDs). I’m wondering if the EFI boot routine might have objected to the MBR scheme, or if exFAT isn’t supported.

I’ll try again with a different partition scheme and FAT32 when I can get access to a Windows box and see if I can get the rescue files booted.

Thanks again, and I’ll keep the thread updated with any progress.


An exFAT formatted partition won’t work. The PR4100 expects Fat32 or it won’t boot from USB.


Thanks, that gives me some hope that there’s life in it still!

Will post back with further progress.


Even if it turns out to be a hardware fault, I wouldn’t worry too much. The most likely culprit is the switching power supply, which can be bad… even if it shows the proper voltages. Often times, they will fail to deliver the proper current under load. The PR4100 uses a standard laptop power supply, with the appropriate specs of course, but I’d have to look them up.

My secondary concern is the RAM, which can also cause strange problems, but it rarely fails these days,


I’ve actually tried different RAM and a new CR2032 just in case, but neither of those helped unfortunately


Here are the PR4100 power supply specifications, just in case.


Length: 900mm
NEMA 5-15P 3 pin plug
IEC-60320-1 C5 3-pin plug
Type A to C5
Rated: 7A 125V


19 volts
4.74 amps
90 watts
IEC 60320-1 C6 3-pin Socket
Inner Diameter: 2.5mm
Outer Diameter: 5.5mm
Barrel Length: 11mm


Many thanks again for taking the time to post all that info.

A friend of mine has agreed to lend me his PR4100 PSU for a few days, just to test the theory that the problem might lie there - I’ll update here with the results, as it would be good to get a definitive answer as to the cause of the red LEDs flashing error.

In other good news, I received a call from WD yesterday from a nice lady who said she was taking over my support case. WD have agreed to cover my problem as I am only two months out of warranty, which is appreciated. Prior to this, I was very dissatisfied with WD’s handling of the case. If a device is labelled ‘Pro’, one should expect that the manufacturer would at least offer to repair or replace the device for a reasonable cost (which they wouldn’t), rather than simply expecting the user to buy a new one as soon as the warranty has expired.

Thankfully, someone at WD has decided that this is not reasonable, and I am expecting an email from WD with further instructions today.


Well you were absolutely right - as soon as I plugged in the other PSU the whole thing came back to life.

So, for future reference - if all the drive bay LEDs are flashing red in sync and the system won’t boot up at all, the problem is the power brick and nothing to do with the enclosure itself.

Thanks for all your help, @dswv42 :+1:


I’m glad you found the source of the problem. Fortunately, power supply failure is somewhat rare, but they are cheap and widely available. It’s also good that WD said they would help, but I strongly advise against sending the entire PR4100 back using their RMA process. If possible, see if they will send you a replacement power supply instead.

I’ve been documenting the functionality of the PR4100 MCU chip and was not aware that a low power condition would trigger 4 flashing hard drive LED lights, so I will add it to my notes. What probably happened is that there was insufficient power for the hard drives to spin up properly, so it may not be a function of the MCU per se, but it’s still a good indicator to look for when troubleshooting.


Unfortunately, now I have the dreaded

Power was lost from the system. Performing file system consistency check. Please wait.

I wonder how long it’s going to lock me out of access, given the 2x3TB RAID 0 and 2x4TB RAID 0 volumes in the system…

I can access the system over SSH though, so that’s a start.


It’s back!

Now I just need that email from WD support with warranty info so I can get a replacement PSU of my own.


Hmmm. So WD sent me a new PSU.


Back to the drudgery of trying to coax a response out of email support in the hopes that they’ll send me a PSU that actually fits the PR4100.


WD Support is so bad that it’s almost comical, and they appear to be getting worse… much worse.


On Friday, two new PSUs arrived via UPS in two separate shipments. Not that I’m complaining…

The NAS is now fully armed and operational once more.


does anyone have rescue files for PR2100, files for PR4100 do not work on my PR2100.
thank you very much.


I have added the rescue files for PR2100.
Simply put all the files (not the rescue directory) on the root a FAT formatted USB drive.