Interested in Learning Basic Water Damage Repair

fluid damage repair isn't magic - it's first of all a simple cleaning job.

but you have to be careful

and yes - some devices are simply dead - the parts are corroded heavily, or the pcb has a "burn" damage through the most layers.

sometimes you can find a workaround - but sometimes not.

the bad part with apple devices is the missing flashing possibility - i mean real flashing - i've hade revived hundrets og cell phones in the past 10 years - sometimes with original hard- and software, sometimes with hacked "underground" stuff. but thats nothing for a hobby - thats hard work with investments most people don't want to know (original hardware has horrible prices - but if you have connections, you can have everything).

some devices not only have bad component damages, the also have software issues and in case of apple devices - "nobody" is able to fix them.

in my active times i desoldered memory chips (bga) from dead phones and soldered them into working phones, only to access the phonebook.

but that will only work if you have the right hardware to read a device.

i also repaired many ipod touch and iphones with fluid damages - sometimes it's pretty bad that the thing is simply dead - even if all components are looking good.

and to answer the last question - no, you cant simply replace the parts. some of them are "glued" and removing that stuff involves heat and pretty aggressive acids. there are a few "maps" of the iphones. but it won't help too much. there are pages for the cell phone geeks - they are mostly in the unlocking or repairing business - you can almost everything - if you have enough money ;-)