The following content will tell you how to upgrade an iPhone 6 Plus from 16GB to 128GB. However, there are some risks on the disassemble process. We do not recommend users to try it.
This is a 16GB iPhone 6 Plus.
First step, disassemble the iPhone 6 Plus.
Remove the display assembly and pull out the motherboard.
Remove the SKhynix 16GB ROM chip from the motherboard.
Old 16GB ROM and new 128GB ROM chip
Of course, iPhone kits are all encrypted, so we will use this tool to replace the ROM serial number.
Put the 128GB ROM into the tool, and then you can replace the serial number.
Using this tool, the hard drive serial number is written 16G 128G hard drive needs to be replaced it
Using this tool, written the serial number of the 16G ROM in to 128G ROM
Install the 128GB ROM.
Now you can see. Available capacity is 113 GB.