This solves a long standing mystery for me. How I could never get the batteries in one of those buggers to last any decent length of time despite only occasional use. Went back to manual calipers in the end.
It's seriously annoying.
I had an old Mitutoyo, cost an arm and a leg around 30 years ago and still working perfectly though the display is tiny by more modern standards, but a few years ago I thought I'd buy one of the new cheap Chinese things as a backup and something handy to do 'near enough' measurements and that I needn't worry too much about leaving lying around down in my workshop.
While it was constructed cheaply, very, and of mostly non solvent resistant plastic for the body instead of non magnetic stainless steel and cutting fluid impervious materials like the Mitu's, it was accurate enough for my sort of use but unfortunately I found it went through batteries like a George Best got through booze and became annoyingly unpredictable as to if it would actually spring into life whenever I went to turn it on and use it.
I browsed around and found that this was a common fault and largely all down to that reason up above.
There are fixes but they involve intrusive poking around and inserting a switch, a bit of a bodge judging by some photos I saw, so I found it easier to simply take the battery out when not in use.
I ended up buying a much newer Mitutoyo off Ebay which has now become my number one goto though probably like yourself, I'm still quite fond of my old
no batteries required verniers largely since I was brought up using them back in the 60's at school when doing Physics and remain comfortable reading them, and I even sometimes still resort to my now rather old but cosseted Moore & Wright micrometers even though they haven't been officially calibrated in years. I do occasionally give them all a check out with some guages and they still seem fine for the enthusiastic amateur stuff I tend to do though which never requires the very fine precision they are well capable of measuring.