how to teardown the battery to replace the BMS so that we can fix the non-genuine battery issue ?
1 Disconnect the new battery and the display flex cables, take down the battery
2 Tear off the original battery bottom cover tape, separate and take out the BMS board
3 Remove the new battery BMS board as well, apply some solid flux on the original BMS board and solid the board to the new battery
4 Paste the battery cover tape on the board, connect the battery to the machine and activate the battery
5 Place the new battery back to the phone and connect the flex cable
6 Connect the display flex cables to the iPhone
7 Turn on the iPhone, go to Settings, non-genuine battery warning disappear
As a final advice, do not try the procedure above if you are not familiar with iPhone repair. The whole process requires special machines and equipment, and especially the professional craft of technique.