A couple of weeks ago we received an iphone 6s in for no power. The phone was clean and did not appear to have been opened before. We plugged it into our charger through the ammeter and the phone pulled the expected current.
We plugged it into the PC and it connected to itunes in DFU mode. We spoke to the client who did not have any important data on the device so we were instructed to attempt a restore. The restore through up error 9 which is known to be a problem with the nand (the memory chip) which put simply is like the hard drive of the phone.
We disassembled the device and tested the power lines to the nand which where all present. Next we checked power to the CPU which was fine as well. Next we decided that it must be a bad connection under the nand or a faulty chip so we went to remove the nand so that it could be reballed. We put the board onto our bottom heater and applied light heat to the top ot the nand so that we could scrape away the black underfill around it, after this we cranked up the heat and went to remove the nand. We applied flux and slid a thin tool underneath to pop it off.
We then cleaned the pads and remaining underfill from the nand areaand did the same on the nand itself. Next we put the nand into our nand programmer to test it, the programmer could read all of the chip data so we knew that the nand itself was ok. We reballed the chip and cleaned it and the logic board. Next we applied flux and refitted the nand into position.
After installation we cleaned the board up and fitted it back into the housing. We connected up to the PC, still in DFU mode and clicked restore. We waited, waited and waited some more until the restore went through without error and the phone came back up as normal!
We tested the phone as far as possible without icloud details and where happy that the repair was successful.
We reassembled the device and sent it back to the owner who was chuffed to have their phone back in full working order.