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820-01521-a stuck at 5V.

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BCN_Techs

Member
Hi,

Have two board with exactly same issue. stack at 5V and 0.10Amps. No water damage, no previous problem.

I was checking other topics. Seems that some of this models with T2 may be firmware issue. So i can see that there is a way to restore it for MBP 2018 but cant find same for MBA 2019. Anyone can help me?
 
B

BCN_Techs

Member
Yes:
PBUS , PPBUS_HS_CPU 12,3V
PPDCIN_G3H-5V
PP5V_G3S - 0V (P5VG3S_EN -0V) and PP5V_S5_LDO also 0. is that ok?
PP3V3_G3H_RTC 3.2V
PP3V3_G3H 3.2V




ALL_SYS_PWRGD -0V
 
2informaticos

2informaticos

Administrator
Staff member
Looks like T2 firmware corruption.
No S5 voltage comes on usually.

Compare your values with these:
"U7800 SYM 1 of 4:
PP3V3_G3H_SOCPMU = 3.37V
PP1V1_SLPS2R = 1.1V
PP3V3_G3H_RTC_X = 3.37V
PP0V8_SLPS2R = 0.8V
PP3V0_G3H_RTC = 3.0V
PP1V2_AWAKE = 1.2V
CPU_C10_GATE_L = 0V
PP1V05_S0SW = 0V
LDO_RTC = 1.5V
PP3V3_G3H_SOCPMU = 3.37V
PP3V3_AWAKE = 3.37V
PP3V3_S5 = 0V"
extracted from this thread
https://boards.rossmanngroup.com/forum/board-repair-troubleshooting/55802-820-01041-stuck-at-5v
 
B

BCN_Techs

Member
Yes seems to be t2 corruption. Anything to do with this shit board or throw it away? Is there any way to restore this firmware like mbp but for mba?
 
B

BCN_Techs

Member
i am trying it with macbook 12 and when plug it says: Cannot Use Thunderbols accesory. Thunderbolt accessories are not supported on this Mac. Any idea? Must try with mbp? dont have one now here.
 
2informaticos

2informaticos

Administrator
Staff member
I think someone reported that not any cable serves.
Maybe 12" machine doesn't serve, or the cable is not compatible.
Also be sure to find the correct USB-C port for DFU recovery.
 
2informaticos

2informaticos

Administrator
Staff member
Cargate de paciencia, todavia no hemos tocado el pico.

Be aware of Amazon delivery, use particulars and cannot be too sure if they don't bring "something" more with the package...
 
B

BCN_Techs

Member
2informaticos said:
Cargate de paciencia, todavia no hemos tocado el pico.

Be aware of Amazon delivery, use particulars and cannot be too sure if they don't bring "something" more with the package...
Click to expand...

I am more afraid of what will come after it:)

Gracias por tu ayuda de siempre informaticos2 y animos
 
B

BCN_Techs

Member
there is no way to put this fu...ing machine in dFU mode like apple's site instruction tell us. also using apple official thunderbolt it says that it's not compatible. Anyone had succes with mba 2018-2019???
 
T

tcampbell34

Member
I have had success using apples USB-C charging cable only on the 2018 A1989 MBP. I tried the same cable on two different 2018 A1990's and got the same error you are getting about "Cannot Use Thunderbolt accessory". I ended up having to buy apple's Thunderbolt 3 cable (With the lightning bolt symbol on the connectors) and then I was able to get both of my A1990's into DFU mode. https://www.apple.com/shop/product/M...91c-cable-08-m

Also, apple's instructions says to hold the keys for 3 seconds but I found that holding them for 7 seconds works better.
 
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