I tidied things up at work, then took the rental Sonic back. That was a painless process other than the bill, and I then walked to the Chevrolet dealer and picked up the Bolt to drive home again.
The battery certainly seems bigger... this is after the short drive home:
It also has a nifty sticker on the window by the charge port:
Yes, I know it's filthy - it's been sitting outside waiting for the battery for 6 weeks :o(