Daughter got too enthusiastic cleaning the keyboard, and can only assume the window cleaner must have carried dirt into the contacts. Columns of keys stopped working.
Battery had died of old age: no longer registered with the diagnostic subsystem.
Followed the instructions and it all came together as described. Keyboard and battery working 100% again.
Lay the screws and fixings out in the order in which you take them out (according to the directions). Makes it easier to locate everything in the reassembly.
Metal Spudger Set
MacBook Replacement Battery
MacBook Santa Rosa/Penryn Upper Case with Keyboard