820-00840 a1708 no boot ,no sound but There is backlight

[tipoti]

hello,
There is backlight but no apple logo. I tried with a different screen, same result. I removed the ssd and tried it, same thing. no boot ,no corrosion, no sound no boot only backlight is on and charging,


no corrosion


What can be the problem ?

 

[2informaticos]

What is CPU core voltage?
Did you check external video and USB activity?
Did you try known good BIOS?

Any history fault?

 

[tipoti]

L7210/20 PPVCCCPU_S0G : 1.0 voltage fixed
no display on external display
When I plug in the usb macos, I see that it draws 5volt 0.045A at the usb output. But the options do not appear on the screen.
I felt the heatsink was a little too hot
I haven't tried the bios

 

[2informaticos]

CPU core should drop to 0.6V when boots.
Is time to try BIOS.

 

[tipoti]

the problem is with the screen
solved