base station flashing blue light

If you have SS2, you need to call SS and have them code a fix to turn off trying to communicate with monitoring.

If SS3, I don't know; I have one which is not connected and I don't get the flashing blue light.

If there's a blue light flashing, it usually means there's a message on the keypad display, pressing on the message icon ("exit" message, or an "x") on the keypad will usually clear it.  Then try arming, then disarming your system.  If the blue light continues to flash, call SS for assistance (SS2 will require that simplisafe sends you a download file to disable the light and turn monitoring off - SS3 may require a base station reboot or something else, but call SS to be sure).