The default working mode is AP mode. Before you access 192.168.0.254, you need to connect your PC to it by cable and set a static IP address for your PC.
Here is an instruction http://www.tp-link.com/en/article/?faqid=378 which can help you.

Thanks!

Procedures followed but still can't gain access.

Check the default settings on the label attached on the router itself.
Is it 192.168.0.254 or 192.168.1.253? Where did you buy it?

Hi, I had a similar issue than 888andrewlo. I also tried the instructions that Matt recommended, but could still not connect. I then did the following:

1. Plugged the device to a power outlet and let it start (until the blue light stopped blinking).
2. I then connected to the default session id using the default password.
3. Opened 192.128.0.254 and got access to the config utility.

Once I changed the device's mode to repeater, configured it and restarted the router, I was again unable to access the setup utility. I disconnected wifi from my laptop and used an ethernet cable to connect to the router. I could get to the setup utility using tplinklogin.net (I assume it had to do with the mode being set to repeater).

I hope this helps.