We need to upgrade the firmware, so we need to use cable. No Wifi.
Also, you can connect to it with cable after you download the firmware because you need internet access to download the firmware.
Please Click Here
Download the firmware, make sure you remember the location where you saved the firmware, then disconnect (wifi to router) from laptop.
Connect to extender using cable,
Log in to the device using a Web browser. The URL is http://www.mywifiext.net.
Click Maintenance > Firmware Upgrade
Click Browse and find the file you just downloaded.
While the firmware is loading, do not interrupt the upgrade process.
Once done, reconfigure the extender.
Let me know the results.