Firstly, the correct address is 192.168.7.2
Make sure you're plugging into the client USB which is the USB mini connector near the LEDs and the RJ45 plug. The USB host connector is down near the uSD card and what appears to be a microUSB is not that, it is an HDMI.
If you're plugging your computer into the correct client USB and have absolutely no other cables plugged into your board, then the board should attain power from this connection. If you have to power it otherwise, then you're likely not plugging into the USB client connector, refer to the diagram for step 1 Connecting to the Beagle
If all connections are correct, you've tried the correct address and it still doesn't work. You can create a new flash uSD card to place a version on the board. That process is here
My personal notes/experience on this are that they claim
it should take as much as 40 minutes to burn the flash, I've seen it take a lot longer; longer than and hour and a half I left it powered overnight after waiting 1.5 hours and when I returned to it in the morning, the four LEDs were finally solid. So, the four LEDs do eventually get to that state; however in my case, 2 separate boards, it took much, much longer than 40 minutes. Note I also have a display and attached a keyboard/mouse so that I could login as root and perform stuff like "ps -ef | grep -i mmc" to see if there were processes which has the mmc block (the flash) as an argument. There were, that's why I decided that the 1.5 hours wasn't yet a lost cause.