A firmware update was in progress on my Archer A7 router when accidentally it got shutdown and after that I am trying to reboot it but nothing is happening. All LEDs are off except power. I've tried resetting it multiple times but nothing is working. What should I do now to get it back to normal.

One thing to mention is that on one of my mobiles this router was not connecting and giving authentication problem since last one month approx.

Any help will be highly appreciated.