A slowly blinking power light means that the FlashRouter was somehow put into Rescue/Restore/Recovery Mode. This usually happens if the reset button was held down for too long.
This may also happen if you have incorrectly tried to update the firmware on your FlashRouter. The first thing to try is a simple reboot of the router to see if it exits restore mode.
If a reboot does not clear up the issue then try to reset and reconfigure your FlashRouter.