Alive!!! It's Alllliiiivvvveeeee!!!
Battery stopped taking a charge after a few years, so bought/installed new battery.
Very easy to remove old / install new battery. HINT: Don't forget to lay out screws in the order/pattern of removal as there is more than one length involved. Pressed start button. Mac turned on and battery started to charge. Success! Then Mac shut itself off after a while. Tried a couple more times with same result (un-commanded shutdown). Re-installed being even more careful. Same deal. Darn. Emailed Ifixit for help. Received email explaining that sometimes old computer does not recognize new battery right away. Battery is sitting in there like a Face Hugger from Alien, but perhaps somehow Mac hasn't noticed. OK. Ran diagnostics per instructions. Computer now agrees that it is the right type of Face Hugger and has been working fine since. Oh boy. Made sure all screws on case back carefully torqued a bit so Face Hugger / Battery can't open case and escape into Med Lab.
Battery swap VERY easy to do IF you have the required Pentalobe from Ifixit. I bought their large assortment of tools and bits and have fearlessly opened up and fixed a few things. The instructions were spot on, but did not offer "now what" troubleshooting suggestions. That may be for the best since I was forced to explain the problem to a competent Issue Wrangler before fixing bayonet and going over the top again. So, if at first the desired result is not achieved, call or write for help before reaching for the can opener.