Chosen Solution
my phone was at 19% and then suddenly jumped to 1% and shut down, I can’t turn it on at all (even tried to hard reset and it didn’t work) so i put it on the charger and now it’s stuck at 1%. it’s been charging for three hours.
Either the battery died or something went bad with charging circuit. Unless you have a multimeter to test battery voltage and connector on the iphone board you may try to replace the battery and hope for the best.
That is the problem of SWI line, Bad Contact of the battery and battery connector cause that issues. Battery have 3 pin to connection. 1 +VE 2 -VE 3- SWI- the center of the battery connector. You can also check by the 3Utool the status like below on the image. First image shows the Detail of the battery means SWI is connected stage.
Second image shows the BSI not connected or faulty or bad contact.
By this way you can find out the proper solution.
