First of all let me thank you for the help this forum provides to many a poor soul in this vast world of NCs.
I am used to working with Fanuc NCs and I have a machine which has a Sinumerik 820T NC. Lately I have been having some issues with it and the only way to solve them was to "reset" (I do not know if this is the appropriate term, but I guess it will do) the NC and reload all the data it had beforehand (this, up till now, was always perform by Siemens techs).
I have been reading the posts in the forum concerning the 810 series and I already have on my side the files from the manufacturer, the TEA1, TEA2 and some other files. I still have to see if the PLC Ladder file is there (in case it is not, how can I get it from the machine, is it possible to do?).
I have the PCIN 4.43 software and I will build the cable I have seen on the posts for DB9 <-> DB25 communication.
My only doubt here is how to interact with the machine for some actions which I detail below:

1. How to backup the programs (my programs) that are in the machine's memory?
2. Can I also backup the TEAs and other System files important for machine recovery in the future? If it is possible, how can it be done through PCIN?
3. Once I have the PCL Ladder file, how it be sent to the machine?

Maybe I am not asking the correct questions but this is where I need your expert opinions and help.
Is there some manual or instruction sheet with a step by step way of putting this NC back in action?
Sorry to be bothering you but, as many before me, there are times where people like you can and will save lives.
Thank you in advance for any guidance you may share.
My personal email is kwakashimazu@gmail.com in case it is more appropriate to communicate through there.
I believe I cannot PM until I reach a certain amount of posts (15 I guess).