The tv remote control, (or one of them, don’t get me started) was ‘saying’ it’s batteries were flat, so I took them out, checked them on my multimeter, and both showed 3.04 volts, and they are rated at 3 volts.
Having other batteries of the same size (3025) laying around the place, I checked them, and found two that showed 3.24 volts on the meter. Problem solved, the remote works again, but this prompts a couple of questions: why doesn’t a 3.04 volts battery do the job, and are all lithium batteries actually higher power than it says on the back of them?