I saw this come up a. few times around the web so I figured it'd be a good thing to post this for people's reference.
First, if it's blinking, there IS an error. Contact support and they will send you a new one. It was quick and easy to get done and they're very helpful.
HOWEVER, if you can't wait for a new supply, you MIGHT be able to get yours running again like I did.
To set up things I have to note that before it started, I did have my phone charging via Surface USB Port. I tried everything I could think of to cause the power supply to 'reset' and
nothing would work. I also have the issue where the supply cord is pulling away
from the magnetic connector. (IMHO, the ONLY poorly designed part of the power
supply.) First, I unplugged it from all sources and left it unplugged for a bit. That
didn't seem to do anything. ODDLY enough, something DID work. I plugged my
PHONE into the USB supply in the Power Block, THEN plugged my Surface Pro 3.It
blinked, then reset. Now it is charging and I have a solid light.
I don't know if it will last, but it does appear that the power block isn't
just a regular power block. I think it's a smart block and it noticed there was
some type of problem and shut down.
Either way, a new one is on the way and I did appear to get this one working in the meantime. I hope this helps someone else.