HP35 problem with a calculator, maybe due to a faulty charger

[aurelio]

Sometimes I review my calculators, checking how they work and then recovering after the parade in their boxes
Of course I also do this with battery packs, charging them every time and checking their efficiency. Today I realized that it's better, maybe mandatory, to check first the functionality of chargers, because who knows, even at rest, they can get damaged.
It happened with one of these and unfortunately it also damaged (it would seem) the unfortunate calculator. I noticed this because while charging it showed strange behavior on the display. I immediately checked the power supply and unfortunately provides about 17V on both sides, instead of the voltage due.
The calculator turns on (with a charge battery pack), but shows erratic behavior by showing meaningless numbers on the display. any idea what might have been damaged?.
A good reason now to do the deep cleaning that we discussed in another thread days ago, and to see the interiors of my HP35 (moreover already repaired by HP years ago, as I see from an internal label), bad for the external label which deserves now the "spaghetti procedure" invented by Alberto, but first of all I must repair it