I’ve explained what a buck converter does here.     A common problem with the CPU vcore circuit is that one of the FETs in the circuit shorts and is always working, even without input to tell it to work.

A common issue with Apple laptops is no backlight due to enable resistors being blown going to the LED driver. This only happens in the case of liquid damage. We repair these issues under our Macbook logic board component level repair

A common issue among Macbook logic boards that do not chime, is no CPU vcore! Vcore is a primary CPU power rail; vcore the CPU will not do anything, and the laptop will not do anything. When troubleshooting the CPU