Need Electrical Help- Turn key and loose all power

I drove to the hardware store today, bought something, came out, turned the key and lost all lights in the dash and no click from the starter. Turned the key back to off then back to acc, got lights again. Then turned to start and lost all lights and no sign of starter engaging.

After a few tries I'm now getting no lights or any response from turning the key from the off position. I've read through these threads https://www.tundras.com/threads/turn-key-nothing-happens.45647/ and https://www.tundras.com/threads/tricky-no-start-issue-06-dc.132704/#post-3371845 and perusing the master Post? These are some of the troubleshooting steps I've tried.
-I've all the fuses in the cab and in the engine compartment
-Voltage on the battery is 12.5 and I hooked it up to a jumper pack and had the same issues
-I jumped the starter relay and didn't get much- I then checked voltage on the 2 contact points and i'm getting 12v on one and 9v on the other, so I think the ground is shorting somewhere.
- I removed and inspected the ECU behind the glove compartment and there is no sign of liquid or corrosion or shorts.

Events leading up to this.
Two weeks ago I had a coffee spill that effected the stereo's volume control buttons
One week ago I did an oil change
2 days ago the passenger window stopped working from both the drivers door switch and passenger door switch.

I really appreciate any help. I've owned this truck 18 years, bought her with a measly 10k on the odometer and now about to hit 240K.

 

Battery cables. Check the main ground cables under the hood.

 

What ^^ @KNABORES said.

Also...

Did you have the battery tested at literally any local auto parts store? Voltage means jack shit if the battery has no CCA. A battery can have 12.5v or more, and still have less than the ~200 CCA required to turn over the engine.

Did you check the in-dash fusebox for water intrustion? (pics & pics & pics, it happens a LOT)
The multi-other-symptom situation is why I ask.

But corrosion inside the terminals (and/or bad grounds) have produced similar problems. And it's more common than you'd think. I even got tung on my 77k mile truck which showed no prior evidence of major corrosion probs.

 

Thanks @KNABORES and @shifty, I followed your suggestions and it turned out to be the Negative battery terminal connection. There was a copper sleave, like a shim to make the post fit and it had corroded. The connection was solid and didn't move when I tried physically manipulate it. I was still stuck at the hardware store, checking all the wires and I used jumper cables t to connect the negative terminal to the engine block and the problem went away, after i couldn't fit under the truck to check the alternator connection. I was able to get it back to my work and the problem persisted and the new solution wasn't working. So I learned how to remove the fuse box. No problem there and then replaced the terminal, That worked like a charm. Thanks Again, I'm up and running!