820-01958 MBA 13" '20 A2179 The CPU becomes very hot

[isa1985]

The CPU becomes very hot immediately after connecting the power supply. Please take a look at the video.

It initially had a broken display, which I replaced. However, I'm not sure if the device was functional when I received it, as I didn't test it. In any case, there are no signs of water damage or moisture.

Video

 

[2informaticos]

What voltages do you get on the board?

 

[isa1985]

19,91V

 

[2informaticos]

"What voltages"
Please, post useful information.

What secondary voltages do you get on the board???

 

[isa1985]

PPBUS_G3H: 12,6v
PP3v3_G3H: 3,3v
PP1V8_SLPS2R: 1,8v
PP3V_G3H
LDO_CORE
LDO_RTC: 1,49v
PMU_VPUMP: 4,98v
PP1v1_SLPS2R: 1,1v
PP3V3_G3H_RTC: 3,29v
PMU_LDO3_OUT: 1,79v
P1V8G3S_EN: 1,8v
P1V8_G3S 1,8v
P5VG3S_EN : 1,8v
P5VG3S_PGOOD
PMU_ACTIVE_READY: 1,79v
P3V3G3S_EN
PPBUS_G3H_SPKRL: 12,64v
PPVIN_S0SW_LCDBKLT_F: 12,64
PPVIN_SW_LCDBKLT_SW: 0,0v
PP1V1_S3: 1,1v
P5VG3S_CS1_L_N: 5,12v
P3V3G3H_VSW:3,3v
CHGR_PHASE1: 12,64v
CHGR_PHASE2: 12,64v

 

[2informaticos]

"PP1V1_S3: 1,1v"
So board turns on, you get RAM voltage.
No idea if boots yet.
What about L7210-30 voltage?

 

[isa1985]

L7210 1.8v
L7230 1.8v

 

[2informaticos]

So even CPU gets core voltage.
PLT_RESET_L comes high?

 

[isa1985]

I urgently need to read the serial number from this circuit board. I have an RT809F ISP Programmer and a 1.8V adapter, and I also have a CH341A. Could you help me read the SoCROM (U4770)? If I can read it, I will be able to see the serial number in a hex editor. Please don't ask why, it's important. Can I directly solder the pins from U4770 to the RT809F and try to read it?

 

[2informaticos]

You must use the 1.8V adapter!
You can connect it to CH341A, or RT809F then.