I have seen a lot of software available to re-program cell phones and etc., but I do not have it on my computer. If you give me a model of phone, I might be able to do a little searching for you. This will defeat all of the work involved in doing what you propose though.
To get the schematics and code for anything relatively new, you are dreaming... This is the companie's intellectual property of which they have spent a ton of money to produce. If you want to reverse engineer the phone, also, good luck.. Usually these are 4-layers, and you do not have xray vision. Also, the density of the board will be a problem.
The processors on-board are also secure, to prevent people from reading their code. I have seen people disabling the protections on some processors, but I am not sure that it will work.
Are you sure this wasn't a self-elected project? I cannot see a teacher assigning this as a project, because it is nearly impossible without actual code and schematics.
Sorry to be negative, but it is extremely difficult to do what you are proposing,
Steve