For the test, I will update the firmware on the router D-Link DIR-815 revision A1.
The router has firmware 1.00 (Fri 06 Aug 2010), on official FTP found version 1.04, b03 (Wed May 15, 2013).
To update the firmware in the D-Link DIR-815 router, perform the following necessary steps:
1) Let’s see the revision on the label under the router and download the new firmware from the official FTP for it http://ftp.dlink.ru/pub/Router/DIR-815/Firmware/
Updating the firmware of the router for the wrong revision can lead to its failure.
2) Open the router settings by typing in the browser address http://192.168.0.1 (can be 192.168.1.1) and enter the default login — admin without password.
3) In the opened interface at the top, open the tab “Tools“, left in the menu select “Firmware“. On the opened page the current version of the firmware will be displayed, if it is older than downloaded, then click “Browse” and select the previously downloaded new firmware file, and then click “Upgrade” to start the update process.
We will wait for the update to be completed, usually about 5 minutes. After the termination the router itself will reboot.
Categorically, you can not turn off the power when the firmware is updated.