Can't jump 2010 prius from jump terminal under hood

Can you get a battery reading from the front using a multimeter?

 

Lots of cables only make electrical contact on one side, even though there are brass teeth on both jaws of the clamp. IIRC, the positive terminal under the hood is metal on one side and plastic on the other. If you don't check to make sure you have the cable clamp oriented the right way, your odds of a successful connection are 50-50.

 

What he ^ said. Look closely at your clip, and you may find the wire is attached to only one jaw. The less expensive clips are, well, mostly non-conductive.

 

How are you connecting your ground (black negative cable)?

Pixel XL ?

 

Wow, lots of good tips. I'd start with @mjoo 's: when jump-starting under the hood, you're connecting your red (post) cable to the jump start terminal, and the the black (neg) cable to what?

This used to be my favourite point, when I was using a charger with alligator clamps:

 

Those boost cable clips are funny. "How cheap can we make it?" The expensive thing is copper. So we use aluminum wire if we can, or smaller gauge copper. We take a small piece of copper, bend it into a square "claw", rivet it to plastic with the wire terminated in a ring terminal also in the rivet. Wait, lets use a steel "claw" with thin copper plating!

It's a wonder no-one is killed!

-I- use a Mueller solid copper clip, with #10 or #8 finely stranded wire. The clip is the smaller type (part number 60C) and the wire is soldered into the end of the clip. The whole clip/wire is covered with a "boot". The "doner" end of the boost cable uses the larger clips, also covered with boots, positive side uses red wire and boots, negative side uses black wire and boots.
Picture attached. I guess for me money is no object, as the cost is around $20. Oh, and I've never actually had to use it on the Prius. But it helps fill the under hatch floor bin.