How/is it possible to hack/output your data (text, pictures) into a fitness tracker?

Question

reverse engineering

After all, you can display your data (your text, pictures) on the bracelet display, use the touch screen as a touchpad, connecting somehow to a computer (bluetooth, for example)?
I would like to understand the principle, and where to dig. How does this process take place? Need to reflash? Do you need to know JAP? If necessary, as far as I know - C ++ is suitable?
This topic is very interesting. I know that this is possible and someone should know how it happens, but I don’t know where to dig and what to learn. I hope for help and I will be very grateful to her)
Mi Band 4 bracelet. But I doubt that the model plays a role in explaining the process)

Answer 1

1. Learn English
2. Search the Internet for mi band 4 sdk
3. See the results, how other people have done it
Yes, it depends on the model of the bracelet
Yes, it can be done for any bracelet - it's a question of cost - for some you may have to examine the chip with a scanning electron microscope or something like that.