Macbook Air takes approx. 8 mn to turn on

Hello Everyone,

I've been encountering an issue for months now.

I have a Macbook Air 13" running on macOS 10.14.1 but the issue started on macOS 10.13, 4 Go of RAM, 128 Go SSD, 1.4GHz dual-core Intel Core i5 from early 2014.

The issue is that if the computer is not plugged with the macSafe, it will turn on randomly, it can be 10mn later or a few hours later after I pressed the power button. However if it is plugged, it'll turn on after approx. 8mn (yes, I counted). Now, before it turns on, right after you push the Power button, you can hear the fan running either it is plugged or not.

Troushooting steps I tried :

Clean the disk & Reinstall the OS--> NOK

Change the battery --> NOK

NVRAM and SMC --> NOK

The thing is, even when the computer turns on, I won't see the charging bar, I'll go straight to the authentication screen so I can't even press the D button at the start up to be able to enter the Apple Hardware Test.

I've honestly tried almost everything, I'm at loss.

Thank you ! 🙂