820-00850 MacBook Pro - Start in recovery - DFU - Revive fails

[samstown]

Hello

User was typing at school, close the lid went home then Mac didn't resume. He did a force shutdown by pressing power button. Mac never restart.
When connected to Apple configuratior, when I plug cable it will show as "recovery". I did a revive, didn't work. I entered DFU, did a revive fail " timeout.." after 16 hours. I did Recovery, DFU with battery.

Data are important, so before trying "Erase all contents and Settings" is there anything else I should check ? While reading a post on this forum, somone had a similar issue but had no P3V3G3, he did a reflow of U7800 and that fix the issue. Should I try that first ?

C8200 = P3V3G3S_SS = 3.39V
R8200 = P3V3G3S_EN = 1.80V

CB701 = PPBUS_G3H = 12.61V
PP1V2_AWAKE = 1.21V
PP1V1_SLPDR = 1.1V

Big coil, diode mode = L7410,7420, 7430, 7210, 7220 = .11
Big coil, diode mode = L7030 = .420
Big coil, diode mode = L8410 = .961

Thanks
Sam

 

[2informaticos]

Check if you can access its SSD in Target Disk mode.

 

[samstown]

Mac doesn't start. no chemie, nothing on the screen. Is there a chance to do target mode in this case ?

I've tried again, revive from recovery or from DFU, keeps failing.

Last option is "erase all" I guess ?

 

[2informaticos]

Possibly nor even restore solve the problem.
Just in case, try first flashing U4770 and revive again.
Don't forget to make backup.

 

[samstown]

thanks. Excuse my ignorance but how to flash U4770 SOC ROM (AB UEC 709 on the pics) ? EEPROM reader, I have it... ? That's the BIOS ?

Need to desolder it or it there a way from the board ? I don't see any port.

Can I take one from a working board and solder it ?

 

[2informaticos]

820-00850-A - Tries to turn on and restarts

I'm sure you can find many videos on Internat about CH341 and that 1.8V adapter. I use different programmer anyway...

boards.rossmanngroup.com

You can find lot of interesting information on other threads, other than yours...