Failed firmware upgrade on WHR-HP-GN wireless router

[Caloy]

My product's name is WHR-HP-GN. Its firmware version was 1.82 but I was trying to upgrade to 1.85. My computer's OS version is Windows 10.

I tried to update my router's firmware to version 1.85 through the web interface accessible at http://192.168.11.1. The update seemed to finish (the progress bar on the web page went to 100%) but then nothing happened next. I waited a while before closing the page and restarting the router since nothing was happening (I guess this was the mistake). After that, the router wasn't working anymore. The power light would go on. The DIAG light would glow solid red for a few seconds after powering on then blink red every few seconds afterward. I searched for various solutions. I tried the 30/30/30 reset method but that didn't do anything. I tried to use tftp to flash firmware onto the router but it just kept timing out. Please help. Thanks.