HP 35S battery drain

[cjsmithuk]

Definitely wired in series here as measured. Also that’s a 5V LDO in there and a 5V voltage detector - I pulled the part numbers down and confirmed it out of circuit.

The inside of mine is slightly different. Not sure if it’s an earlier or later one this one. I’ve attached the photo from mine. Note the use of electrolytic rather than tantalum capacitors compared to the one you posted.

Anyway this is useless as it stands