820-01041 No power

[tcampbell34]

Hello guys. I got another 820-01041 board that does not turn on but has no signs of liquid damage at all. If you connect the charger to the board with the battery connected, it goes to 20v 1.4 amps, fans spin, and the screen turns on and shows a low battery symbol and then it turns off. Without the battery connected, the board gets 20v and only goes up to about 200-250ma for a second before it drops down to 20v and 0 amps and stays there. No fan spin or image on screen with battery disconnected. I have not found any shorts and the board is completely spotless so no sure where to look first. Here are some basic measurements.

PPBUS_G3H - 12.6
PP3V3_G3H_T - 3.3
PP3V3_G3H_RTC_X - 3.37
PP1V8_G3S - 1.8
PP5V_G3S - 5.13
PP3V3_G3S_T - 3.3
PP3V3_G3S_X - 3.3
PP1V05_PRIM - 0
PP1V8_SLPS2R - 1.8
PP0V8_SLPS2R - 0.8
PP1V1_SLPS2R - 1.09
PM_SLP_S5_L - 0

 

[2informaticos]

Could be T2 firmware issue, so start with DFU recovery.
Several threads on the forum explain how to do it...

 

[tcampbell34]

I tried the T2 firmware restore on this but it was not going into DFU mode and was giving me an error that the thunderbolt accessory was not supported on my host mac. While I was checking the rails, it randomly decided to boot off the charger. I put it back in the case with the battery and it boots now and seems to work fine but the keyboard backlight is not working. I tried putting this board in another topcase and it still has no keyboard backlight, so seems to be an issue with the board. The keyboard itself works fine and diagnostics reports no issues found. What controls the keyboard backlight on these boards?

 

[tcampbell34]

I was able to restore the keyboard backlight on this after a lot of trial and error. Apparently it had something to do with me upgrading this mac to the latest version of Catalina (10.15.4). It had no keyboard backlight and the setting to adjust keyboard backlight were all missing from the settings menu, as if it were not installed. I downgraded the computer to Mojave (10.14.6) but still had no keyboard backlight. I found a post on other website about a similar issue where the person had to restore back even further to get the keyboard backlight working again. I had to find a copy of Mojave (10.14.0) online, because Apple does not have it anymore, and then installed that from a USB drive on this macbook and once that finished, keyboard backlight is working again. Very strange issue but thought I'd post this in case anyone else has this stupid issue.

 

[2informaticos]

Thanks a lot for feedback.
Is really strange issue/solution and this can seve time of other people.