Not booting up Battery is at 2.4V should be 3.82V
How can I bootup bypassing battery to check before having to buy a new battery?
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There must be a battery installed for the device to boot. You’re battery voltage is too low but the charge circuit should still recognize it and charge it, allowing for a boot process once the battery gets to the proper voltage. Leave the device charged overnight to see if this helps.
If the battery is not charging properly, it could be a battery issue or a charge circuit issue. I would do the following (in order):
- Always try another Lightning cable and charger, preferably Apple original or MFi certified units.
- The Lightning cable 8-pin connector should be sitting flush with the housing and completely inserted. If it is not, there could be lint/dust/debris inside the port impeding a proper connection. You can clean it out with a toothpick, fine point tweezers or a dental pick. Just be careful not to damage the pins inside the Lightning Port.
- Change the battery. The battery is the weakest link in the entire phone and certainly for charger related issues. It is also the easiest thing to replace. Use a battery utility, such as coconutBattery (for Mac) or 3uTools (for Windows) to test the battery prior to removal. Anything less than 70% of design capacity will require replacement.
- If the battery is in good condition, you can use a USB Ammeter to determine if the phone is really drawing current when it says it's charging. If it isn't drawing current, then I would change the Lightning/Charge Port.
- If a new battery and charge port still don't resolve the issue, then you either have faulty replacement parts (possible) or a logic board issue. There is an IC (commonly referred to as Tristar) responsible for communicating with the charging device and uncertified chargers can damage it. Unplug the battery and connect a known-good (preferably Apple original or MFi) charger to the phone. A properly working phone will show an Apple logo and boot loop. If the Tristar IC is bad then the phone will not do anything.
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Thank you for a very well thought out testing process. will try the troubleshooting described and let you know the outcome.
Good luck...let us know how it works out or if you have any additional questions.
@refectio replaced battery ammeter .43 Amp phone was on DFU mode. Selected restore and upgrade after message (preparing phone for restore) phone displayed Apple logo, iTunes displayed (serial number: n/a) then a popup (unknow error occur(9)).new battery got warm and now ammeter is at 0.00 Amps old battery is drawing 0.01 Amps like before. Any suggestions ?
Error 9 is typically NAND related. Check the two NAND lines from the PMIC. If they are good, then the NAND may need to be reprogrammed or replaced.
The two NAND lines are PP0V9_NAND & PP3V0_NAND. You can find the schematics by searching online - "iPhone 7 Plus Schematic" - (we can't share them here). As for programming the NAND metadata, you need an expensive and specialized programmer...this is not a DIY kind of thing.
The battery shield should have no impact if the battery is securely connected.
