My connector would not release as shown, using reasonable force, so I unbolted the battery to slide it back, then was able to slide the connector back. Ultimately, it popped up on its own - suggest review of this process. No drama, nothing broken, all good.

Used a genuine Apple replacement battery and followed instructions above, worked perfectly. Thank goodness iFixit has those tricky Y0 Tri-point screwdrivers, it might have been quite a challenge without this tutorial and the right tool. After install, checked new battery info in Apple (menu)>About this Mac>System Report>Power (OS-Mojave 10.14) and it showed full power and the new battery was on its second cycle. iFixit battery kit with known high-quality battery and correct tools is simple solution. I’ve learned to trust these folks, they are doing this to help others while earning an honest living, not trying to get rich quick. Thanks!