No. A flashing blue LED is not in the book. This suggests that something has gone wrong somewhere. It is possible to revert the LED to a normal working condition.
First of all you need to enable SSH. I need to make an FAQ I could use to just past in here, but if you search the community for “SSH” and “PuTTY” then you’ll quickly find instructions how to do this written my myself and others.
For your info:
Once you have signed in to the MBL’s operating system as user “root”, issue the following commands . . .
echo no > /sys/class/leds/a3g_led/blink
Whatever colour is showing, the above command will stop it blinking. After that just issue the command logout to end the terminal session.
… but it should not be flashing blue.