820-00850 5V 270mA

[No-Clean]

Board had little corrosion at C7226 and cap fell off with a little push, check before removing cap and there was no short

Restoring T2 gives error about giving up waiting to transition from DFU to DFU

3v3_G3H_RTC : 3.3V
PP1V1_SLPS2R : 1.1V
PP1V8_SLPS2R : 1.8V
PP0V8_SLPS2R : 0.7V
PP1V2_AWAKE : 1.1V
PP3V3_AWAKE : 3.3V
PP1V1_SLPS2R : 1.1V
PP5V_G3S 0V

 

[2informaticos]

Pufff, corrosion sign at CPU power supply not good at all.
Check diode mode to ground on all MLB's coils and compare with good board.

 

[No-Clean]

Only C7226 was affected by corrosion and was not shorted.
Diode measurements are fine, low resistance CPU lines were measured in ohms and were also fine.
Forgot to mention PPBUS is 12.2V

 

[2informaticos]

Check diode mode to ground on SSD power rails.

 

[No-Clean]

All SSD power rails are on par with working board as far as diode measurements, they are of course missing voltage.

 

[2informaticos]

Flash SoC ROM and try DFU again.

 

[No-Clean]

I dont have a programmer for this ROM chip, I do have another one of this boards so I transplanted the ROM chip and did a restore and get the same error as before.

 

[2informaticos]

I expected to get a numeric code of that error.

Try DFU connecting a battery holding some charge.

 

[No-Clean]

With a charged battery the Mac started up, this told me that one or more of the CD3215 was the problem, so I did more and more testing and found that one of the ports (The one used to restore) when plugging a USB Tester did not give me the 5V out, so I replaced it and boom! Mac working!

Thanks so much!