Can the ROM be read and flashed back on Casio watches?

I once bought a solar G-shock but the watch UI is horrible: it does not display the battery charge anywhere on the watch. Instead, it wants you to install a Casio app that connects to the watch via BT. However, even the app doesn't show the battery charge with more than a few scrambled pixels in a small icon. So, useless.

I still don't know how much battery I had left at the time: I eventually got a low battery warning during the winter with no good sunlight to charge it and so I forgot about the watch. You would think a solar watch would want to boast with a highly visible battery level indicator on the screen, and also because it would be a very useful thing.

If the ROMs are hackable I'd be interested in looking at the assembly if for nothing else but to fix that battery level indicator.

I doubt that they use any kind of reprogrammable memory, but you can swap out the entire board like I did: https://github.com/carrotIndustries/pluto