The unbricking needs to be done on the Sd slot built in to the raspberry pi, not a usb adaptor
When it wasn't working for you last time, where you trying to use a usb Sd reader?
one thing you should look out for which may be why it wasnt working when you had it soldered to the SD adapter, is that some adapters are reversed, look at the top corner and see if it is the same side as the one in the picture you are following, if the keyed corner is on the opposite side of the adapter when open you need to solder the wires in the opposite direction