One protip, with which I've resurrected countless laptops and even a server:
Shut it down, pull the power chord, remove the battery (or hold down the battery reset button on modern laptops), then hold the power on button for a couple of seconds.
It'll drain all capacitors and remaining voltage.

Or: a software glitch in need of a hard reset.
Most electronics have a lot of capacitors to stabilize the input voltage.
When the device is in some low power state, it can take a surprisingly long time until these run out of their charge after disconnecting external power.

This is actually part of it though it's more nuanced with smaller form devices, than say a desktop computer, that run on very little power and have parts from lots of different manufacturers rather than integrated motherboards.

Firmware sometimes needs a hard reset to get past bugs, and sometimes a capacitor or two have enough power to keep a low power memory chip active for days, weeks, months, or longer.

Problem at a high level is with devices that are not well integrated because a lot of products these days are a mishmash of pre-made rather than purpose-made components from various companies, and some have some kind of firmware running in local memory and they try to cache information rather than reloading each time to speed up startup times.

Could be a motor driver chip for focusing the lens from some fly-by-night manufacturer with buggy firmware throws an error that the main device interprets as a potential for a catastrophic failure and refuses to start up to prevent what it thinks might cause damage or user injury. But maybe really its just a bug.

That chip stays charged and continues to throw the error when the main board does startup checks and every time the battery is put back in, it replenishes the charge in the driver chip. Finally once it loses charge and has to load from scratch and actually runs the checks again it doesn't remember that it previously threw an error and the current checks don't trigger the error anymore, so it's "fixed". Could be that there is a part close to catastrophic failure or could have been a bug that triggered it, but for now it's fine. Just a wild top of my head example, but the basic idea is there. Also, could be something physically is lose and it got knocked into a place where it's making enough contact this time, but might get lose again shortly after.

Always hard to say without a trained technician or a good product with good error handling. But good error handling isn't profitable anymore. That means more development and testing time up front and less likelihood of the user having to replace the product sooner and since competition is more scarce these days, there's no incentive to make better, longer lasting products.

It wouldn't surprise me if an accidental load of static electricity got inside the electronics. Would certainly take a while to dissipate through air, especially air trapped inside the device.

Nevertheless, it might be worth trying grounding all the terminals that usually connect to the battery.