iphone 7 no power up

Hello Dr Jessa,
Could you give me your prognosis?

https://forum.ipadrehab.com/forum/ip...phone-7-no-pow...

[lots2learn]

Woops I was supposed to change Tigris FIRST, then Tristar?

[lots2learn]

15/10/2020

Replaced Tristar

1. USB - 0mA current draw - boots? to Apple logo - logo gone(half a second) - boots? to Apple logo
2. DCPS - 0mA

...

[lots2learn]

When I lightly rub my finger over the surface of the IC, or gently run my tweezers (NOT scrape!)along the surface of the board. See picture.

[lots2learn]

I asked the person who confirmed that they were the original owner whether the phone had ever been exposed to liquid/water damage. They said no.
...

[lots2learn]

iphone 7 No power up

Out of the frame with known good battery, charge flex and screen

1. USB - 0mA current draw no boot
2. DCPS - 0mA before

...

[lots2learn]

I do have one final question. This is an unlocked motherboard. If, for arguments sake I successfully transferred CPU(yes probably next to impossible...

[lots2learn]

WATER damage! Enjoy the wonderful view of a water damaged phone! Staring me in the face ALL the time as plunged into the eternal rabbit hole!. What a...

[lots2learn]

Yes I did press on the battery connector - for 5 seconds but entire time was the magic word I needed to hear, which you said just now.. so this time...

[lots2learn]

Just checked my old records for working on this device. As it turns out I did attempt to update the software before mucking around with the ICs.........

[lots2learn]

I've replaced Tigris, twice. I think I've ruled out Tigris, but I'm still getting the gas gauge issue. I COULD just do another TRISTAR replacement and...

[lots2learn]

Hello tojaert. Thanks for the reply.

I think I get your point. The first thing I should have done to was try and reinstall the software,...

[lots2learn]

Hello tojaert thanks for the reply.
Not sure what you mean about reading tristar's status. If you are asking whether I have a Tristar tester, then...

[lots2learn]

Reballed Tigris - retested no difference.
Replaced Tigris with another one from a different supplier - Rossmann Group.
Behaviour is as with...

[lots2learn]

Thanks for the response. I checked the motherboard's battery connector under the microscope comparing with the battery connector from the known good motherboard....

[lots2learn]

(DCPS after inserting power 5v reverse polarity - soon after I disconnected and reconnected correctly - failure wasn't immediate but later on when trying...

[lots2learn]

Hello tojaert,
Thanks
I will try your last advice and see if BB_CPU is actually working/accepting the software and post

[lots2learn]

Hello tojaert.
Thanks for the reply and insights.
Ok, to be sure I understand you correctly, When the iphone is in setup mode after a reset...

[lots2learn]

Hello tojaert. Thankyou

The original 6s phone I am investigating is in setup mode stuck on searching and unable to activate. When I connected...

[lots2learn]

Initially I thought my soldering was causing this, now I'm not so sure. I took a working icloud locked motherboard and measured the power rails with my...