The blinking red light on the Tenda N3 was the only thing keeping Elias awake at 2:00 AM.
...T... E... N... D... A...
You downloaded the hardware version V2 firmware for a V1 device. Tenda N3 has revisions (V1, V2, V3). Fix: Check the sticker on the back of the extender. It will say "Model: N3 Vx.x". Download the exact version. Tenda N3 Firmware Update