Chosen Solution
Hi All Have an iPhone 6S that will not turn on at all. Tried putting a charged battery in and a new screen still will not turn on at all. Could it be the U2 chip? I thought even though it was faulty it would still turn on with a charged battery.
Even a defective Tristar should get to the Logo screen…usually. Is you phone detected by iTunes if connected to a computer? Your problem sounds more pervasive. Have you probed the circuit board, primarily PP_VCC_MAIN & PP_BATT_VCC to see if they are shorted? When “powered” by a known-good battery, do you see the proper voltage levels? This is the first thing to check, after the battery, on dead devices. If you see shorts or no voltages, then this phone will have to be looked at by an experienced micro-solderer.
