How to edit phone firmware?

Question

Mobile devices

I have a working touch phone Samsung GT-C3322. I want to rip open the firmware of the phone, play around with it, put it back together and install it on the device, and then repeat it again and again until I get bored. I understand a little about programming and working with a soldering iron, but I don’t understand at all from which side and how I should approach this issue. Tell me where to start and in what direction to dig?

PS. if this requires some kind of hardware, paid software or free time, then this is not a

PS2 problem. The question is not "how to change / change / replace the firmware", but rather "how to edit the firmware"

PS3. If editing the firmware is more difficult than writing it from scratch, then the question then is how to write it? What tools and technologies do I need?

Answer 1

Instructions are easy to google.
For example
www.gsmforum.ru/threads/118767-%D0%BA%D0%B0%D0%BA-...