iPhone 6 battery drain problem

Dear Sir
my iPhone 6 battery drains even when i completely turn the phone off. ( charge decreases 10 to 15 percent from night to morning ).
battery health is in maximum capacity (%93)
i made the test for TRISTAR IC (U1700) as you explain in the “ what to do when your iPhone 6 won’t charge “ blog post and it’s video and the measured voltage is almost OK ( more than 2 volts). off course i don’t have the dongle and software that you use in your video.
i made some another tests to make sure which part of phone is consuming battery :
i totally disconnect the charging board, speaker, vibration motor , LCD screen and main camera from the logic board and left only the logic board connected to battery and still the battery is draining!
another problem with this phone is that the phone Restart sometimes randomly.
please help me to find out the problem
best regards
Ali