Hi Yara! I tried to ping you on your youtube videos, but you have disabled the comments. You'll need to purcahse few tools. Dont worry they should be easily available locally.
I've taken a video while I was working. I'll see if I can upload it.
Try this page with complete tutorial. https://www.superhouse.tv/31-sonoff-tasmota-installation-and-configuration/
I have the exact same problem,
I bought 18 units and I have at least 6 units gone bad.
I am so upset because my apartment is ,likes your Yara Bradão , everything brand new installed.
Now I cant turn the lights on.
I will try what Kishi suggest.
I had to flashed TASMOTA to make them work again