It would have helped get answers if you included the model number, since Lenovo made a lot of different models, and some solutions only help with certain ones. That said, on most of them there's a slide-switch, front or side, which turns WiFi on/off.
The LOCK symbol is asking for a Supervisor password; if you do not know it, all the youtube videos will not help, you own a large doorstop now. There is a similar question in the fixit section under the other designation for IBM laptops (IBM + Lenovo). Look there, there are far fewer entries to look through.
You need to replace with the proper board, there are several T61 mbds. If you want to, disassemble the laptop (directions can be found on IBM's website, just google "T61 repair manual") and then search eBay for the same one.