Not able to login to the ssh and also to the online portal

i have a beaglebone black purchased few months back.
i used it frequently. But few days back when i was setting the gateway route… something went wrong and the beagleboard stopped working.
i flashed it again with OS (BBB-eMMC-flasher-debian-7.8-lxde-armhf-2015-03-01-2gb) . But the Usr0 was flashing incredibly fast and nothing was working as expected.

i flashed it again for about 10 times with the same os. Still no solution.
Yesterday i tried it flashing with the (BBB-eMMC-flasher-debian-7.8-lxde-armhf-2015-07-06-2gb) but still the same problem is there. Usr0 blinking too fast and cant do anything on the board .

what to do ? Is the board bricked ?

please help.