How to tell if the bios file is corrupted on the MacBooks

[mnciks11]

Hello guys

How to tell on MacBook if the bios is corrupted or not, on windows laptop I observe the behavior, measure the bios, usually windows laptops they will turn on and have nothing on the screen, the fan will usually spin one way and none stop, and more signs and measurements

But with MacBooks im clueless, will you get a chime sound if the bios is corrupted, I don't think so anyway, be kindly share your views

I have an 820-000165 machine, turns on, doesn't chime, the screen turns on but nothing on the screen, i have 1.8v on the cpu, i have checked the board, but judging by the behavior, what can be missing, is it bios?

[mnciks11]

Re: How to tell if the bios file is corrupted on the MacBooks

I have the following necessary volts:

-1.05v P1V05S0 LL
-1.2v PPDR_S3_REG
-5v /3v power supply
-3.3v_S5_REG
-1.8v PPVCC_S0_CPU_PH1
-24v from the baclight buck conveter

[mnciks11]

Re: How to tell if the bios file is corrupted on the MacBooks

Kindly find photo attached

[piernov]

Re: How to tell if the bios file is corrupted on the MacBooks

Try PRAM reset.
Remove SSD and check if you get blinking question mark folder after a minute or 2.

[mnciks11]

Re: How to tell if the bios file is corrupted on the MacBooks

Try PRAM reset.
Remove SSD and check if you get blinking question mark folder after a minute or 2.

I did that brother, no question mark, with or without the the SSD

Let me measure PRAM reset, but keep in my that i do have ram voltage

I will update you just now

[mnciks11]

Re: How to tell if the bios file is corrupted on the MacBooks

I feel the need to share a solution on my case

I reprogram the bios, the laptop started to display and indicated that the battery is low on the screen...With a corrupted bios chip you won’t have a chime sound on macbooks, cpu volts was available, ram volts was available, 1.05 volts was available, most necessary volts were available but I didn’t have any chime sound and display , keep in mind that there a was backlight on the screen but no image

That why I reprogrammed the bios chip and the machine started to display