I’m still puzzling why Apple still coming out with 16GB model where the usable storage are very low even for a normal usage.
Here is a DIYer upgraded it 16GB version of iPhone 6s to 128GB by replacing the flash memory on the board. It’s cheaper to buy a 16GB iPhone 6s + 128GB flash memory than a 128GB iPhone 6s.
Note: This is a complicated and required high skill level to modify the flash memory. It may permanently damage the device as it required very high temperature to remove the chipset.
First he pry open the iPhone 6s and remove all the screw to access to the mainboard.
The mainboard in the middle
Locate the flash memory “SKhynic” that need to be taken out and replace with a new 128GB of flash chip.
Removing the chip required a very high temperature gun to un-solder it.
The 16GB and 128GB flash chips
All flash memory carry an unique serial number individually thus replacing new chip would required a special machine to change the memory’s serial number so it can be read by the board.
Once done, the iPhone 6s would need to reset and rebuild the software by connecting it to iTunes in DFU mode.
Tadaa!!!! Upgraded the iPhone 6s from 16GB to 128GB.