I've been exploring my new HP12C Platinum +, the one with 2 batteries and found that the self test menu that we reach when we press <ON> + <g> + <ENTER> now display 4 alternatives. I'm trying to include the photos here but I was unable so far.
The alternative 1 turns all elements in disply on; any will make the calculator return to the 4 alternatives menu. Number 2 will start the self test that runs for some 10 seconds and then display "ChE--564Ah" string. Apparently there is no way out of this and I had to turn the device off. Alternative 3 will turn everything on again, but will require that we press all keys in column sequence to turn everything off. Any other key wiil bring tha calculator back to test menu. Number 4 will display "4059760 h2".
Other other selftests are documented in the User guide: <ON> + </>, <ON> + <x>, <on> + <-> and <ON> + <+>. The test for the HP12C+ <ON> + <g> will n ot operate with new machine.
There is not a sign of a connector near the bottom of the batteries as we had in the new HP12c+.
I will try to include the images I made as soon as I learn how to do it.
José