Hi all,
I'm trying to fix an IPAD 6, 2018, A1893 WIFI.
It does not turn on and does not enter recovery or dfu mode.
History
The device was working before, but did intermittently reset.
I gathered two panic logs:
"panicString" : "Attempting to forcibly halt cpu 0\ncpu 0 failed to halt with error -5: halt not supported for this configuration
"panicString" : "panic(cpu 0 caller 0xfffffff020e14724): nvme: "AppleEmbeddedNVMeController. Controller fatal bit set. Write.
I attempted an IOS update to the newest available version using 3u tools. According to 3u tools, the update was completed, but the device never turned on again.
Current state
I removed the main board from the housing.
When connecting the device to a dc power supply at 4V, the current draw at the battery connector (battery disconnected) is 800µA, when pressing the power button the current draw changes to about 20mA.
When additionally connecting to a charger, the current draw at the power supply drops to 0. My USB ammeter does not show any current draw, but I assume the current is supplied by the charger.
The supply voltages at the A10 SOC are all in range as specified in the schematic, with the only exception of PPVDD_GPU and PPVDD_GPU_SRAM being 0 V. This is the case with only dc power supply, only charger or both connected.
There is no SPI or I2C communication to the PMU or TRISTAR.
When connecting the tamarin cable, there is communication with the tristar and a reset can be triggered (RESET_TS_TO_SYSTEM is pulled low for several 100th ms).
Assumptions (based on my measurements)
The TRISTAR and the PMU are ok.
The A10 is not executing software (for whatever reason)
Questions
- Is the missing GPU voltage a problem during initial boot sequence?
- What signals should I check?
- What problem is most likely given the history (A10 solder connection issue, NAND defect, ...)?
Any infos, hints or insights are appreciated.
I'm trying to fix an IPAD 6, 2018, A1893 WIFI.
It does not turn on and does not enter recovery or dfu mode.
History
The device was working before, but did intermittently reset.
I gathered two panic logs:
"panicString" : "Attempting to forcibly halt cpu 0\ncpu 0 failed to halt with error -5: halt not supported for this configuration
"panicString" : "panic(cpu 0 caller 0xfffffff020e14724): nvme: "AppleEmbeddedNVMeController. Controller fatal bit set. Write.
I attempted an IOS update to the newest available version using 3u tools. According to 3u tools, the update was completed, but the device never turned on again.
Current state
I removed the main board from the housing.
When connecting the device to a dc power supply at 4V, the current draw at the battery connector (battery disconnected) is 800µA, when pressing the power button the current draw changes to about 20mA.
When additionally connecting to a charger, the current draw at the power supply drops to 0. My USB ammeter does not show any current draw, but I assume the current is supplied by the charger.
The supply voltages at the A10 SOC are all in range as specified in the schematic, with the only exception of PPVDD_GPU and PPVDD_GPU_SRAM being 0 V. This is the case with only dc power supply, only charger or both connected.
There is no SPI or I2C communication to the PMU or TRISTAR.
When connecting the tamarin cable, there is communication with the tristar and a reset can be triggered (RESET_TS_TO_SYSTEM is pulled low for several 100th ms).
Assumptions (based on my measurements)
The TRISTAR and the PMU are ok.
The A10 is not executing software (for whatever reason)
Questions
- Is the missing GPU voltage a problem during initial boot sequence?
- What signals should I check?
- What problem is most likely given the history (A10 solder connection issue, NAND defect, ...)?
Any infos, hints or insights are appreciated.
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