This board works fine with internal display, but nothing on the MDP.

The measures below are with an external display connected to MDP A

PPBUS_G3H =12.6V

TBT_A_HV_EN =0V
PP15V_TBT=0V
TBT_A_HPD =3.3V
PP3V3_S4_TBTAPWR =3.3V
PP3V3RHV_S4_TBTAPWR_F=3.3V

On U2800:
PP1V05_TBTRDV = 1.01V
PP1V05_TBT = 1.01V
P1V05TBT_SW = 0.95V
PP1V05_TBTCIO = 1.00V
PP3V3_S4_TBT = 3.3V
PP3V3_S4_TBT_F = 3.3V
PP3V3_TBTLC = 3.3V
PP3V3_TBTRDV = 3.3V

I checked all the above points also on a...

The diode D7710 should be ok with these measures in diode mode: 0.3V in one way and 3V in the other. I confirmed on a working board.

About [B]BKLT_EN high but LCDBKLT_EN_L is not being pulled down[/B]​, indeed I2C_BKLT_SDA was not reaching the LCD, trace cut close to C8358, also damaged.

After repair, backlight is finally present. BKLT_SD is now at 6V, 0V is not even needed. Also confirmed on a working board. Then LCDBKLT_EN_L is at 8.8V

Thanks for the support! In future I will always check these communication lines first...The diode D7710 should be ok with

Thanks for this information.
I did the PRAM reset, no change.
SMC_LID =3.4V
Tested R7732, R7731: values are ok, traces too.
Tested D7710: in diode mode: 0.3V in one way and 3V in the other.

I replaced U7700: still no backlight, the above measurements are the same.

What can be the next move? Replace Q7701?

On this board I have no backlight, but I can see that an image is present when I put a strong light behind the lid.

On LCD connector:
PPVOUT_S0_LCDBKLT =0V - resistance to ground on this pin: 163ko
LCD_HPD_CONN =2.5V
PP5VR3V3_SW_LCD =5V
EDP_PANEL_PWR_OR_PSR_EN =3.3V

EDP_PANEL_PWR =3.3V
LCD_PSR_EN =0V
EDP_BKLT_EN =3.3V

EDP_BKLT_PSR_EN =3.3V
LCDBKLT_EN_L =12.5V

On U7700:
VDDD =5V
VDDA =5V
EN =3.3V
SD =12.4V
VSENSE_N =12.6V
VSENSE_P =12.6V

Any suggestion on...

Worst case you can buy the same dead motherboard from Aliexpress, for a coil it should be ok (maybe expensive for just one coil, but components can be reused on other boards later)
[url]https://www.aliexpress.com/item/1005006168718584.html?spm=a2g0o.productlist.main.41.2b88n06Cn06CMl&algo_pvid=3c2efda4-4fff-491c-9fb0-5b93832948d0&algo_exp_id=3c2efda4-4fff-491c-9fb0-5b93832948d0-20&pdp_npi=4%40dis%21EUR%2156.26%2156.26%21%21%21432.44%21432.44%21%402103085b17163040446358848eb141%2112000036087583676%21sea%21PT%21170463335%21&curPageLogUid=zKymciV3uhmh&utparam-url=scene%...

PPBUS_G3H is 12.6V on both sides of F7140, stable, no pulses
PP1V2_S5_SMC_VDDC =1.2V
PP3V3_S5_AVREF_SMC =0.2V... indeed there is corrosion under U5110; replaced it, now it chimes and blink folder. Thanks a lot for this so fast pinpointing!...

Hi,
This board has slight water damages. No fan spin.
When I power on, I got:
PM_SLP_S4_L
PM_SLP_S5_L
PM_SLP_S3_L
ALL_SYS_PWRGD
all go to 3.3V, then back to 0V after 1s
PP5V_S5=5V
PP3V3_S5=3.3V
SMC_S4_WAKESRC_EN remains at 0V.
With SMC bypass, fan spins full speed.
Can you help on troubleshooting SMC_S4_WAKESRC_EN missing?...