Ground wires

The yellow wire isn't a ground wire, it is the return wire that is used as a signal ground for the OEM radio. What do the two key inputs on the new radio do? If they are looking for a simple on off switch to control functions the factory steering buttons are not going to work for that. Internally to the steering controls there are different resistance levels that happen with each button plus a base resistance that tells the unit that you are not pushing any buttons.

So, since I connected the KEY1 and KEY2 wires to the blue and lt. green wires coming out of my vehicle, that us not correct?
The KEY1 and KEY2 wires are for the steering wheel controls on my steering wheel and Pin6 (yellow wire) is the ground.

How about the black wire in the harness of the 20 pin connector, is it ground?

What are the KEY1 and KEY2 wires supposed to do? If they are power feeds then the wires you are asking about have nothing to do with that.
No the black wire is not ground. Toyota doesn't use black for ground. In fact they have their own color code for most everything and even change wire colors based on the connection points and systems. Same with power feeds. There are at least 4 different colors just for power to the factory stereo.
What make and model is the new radio? I might be able to get the wiring for it and see what you need to connect to what if the wiring diagram is online.

It's a Chinese brand, Android Binize. It came with GPS, BT, Wi-Fi, 3G, Backup camera connection, Dual USB, Steering Wheel interface, Mirrorlink, RCA audio and video outputs and inputs, AUX, built-in mic, google playstoe, etc., etc., etc. for under $100.00.
So for ground, what can I do? Can I use the black ground wire that came with the radio or can I just take the yellow wire and clamp it to bare metal?

The yellow wire is not a ground it connected to the ground feed in the old radio. All three wires now are connected to nothing but each other through different resisters in the switch.
Went and found their site but don't see any wiring diagrams there, did find some information on YouTube. If I understood it correctly you would connect the SW1 and SW2 wires to the light green and blue wires but they don't talk about the rest. I suspect that you would need to connect the yellow wire to a good ground that also grounds the radio so it can see the switches activate. Then run the set-up program to see if it all works. For the ground I would run a good ground from a different place and ground the radio and the yellow wire to it.

Okay. Sounds good. Let me try that. Thanks.