P645-M will not display Acer splash screen. What is the POST sequence?

My P645-M was working flawlessly until an attempted boot one morning. Power and WiFi lights light up blue as per normal and then everything switches off after about 8 seconds. No Acer splash screen and no keyboard backlight on powering up. No indication of any display activity, or fan or keyboard activity. I have pulled the SSD and wireless card and it makes no difference. No sign of fan spin up. A battery reset does momentarily kick the fan off. Battery appears to still charge correctly based on the front LED changing colour from orange to purple.

Does anybody know the POST sequence of these units? At the moment I'm thinking either a dead display, keyboard or something else that is preventing the Acer splash screen from showing. No change on trying to boot device when connected to Acer docking station. Dead, nadda, except for the power and wi fi purple lights showing for 8 seconds when the power button is pressed. Thanks for any help. Dead motherboard? Why oh why???

Accepted answers

billsey

It sounds like you are not getting to POST. The sequence prior to POST, I believe, is first the contact closure on the power switch has the MB initialize power, then the processor initializes, then it starts POST with a memory test. Since it sounds like things start to power up, then shut down, it's either an issue with the power circuit, where voltages don't meet specs or an issue with the processor not completing initialization. If it starts into POST and the first step fails you get a long beep to say the memory is having an issue. No beep means you aren't getting that far.

All comments

billsey

It sounds like you are not getting to POST. The sequence prior to POST, I believe, is first the contact closure on the power switch has the MB initialize power, then the processor initializes, then it starts POST with a memory test. Since it sounds like things start to power up, then shut down, it's either an issue with the power circuit, where voltages don't meet specs or an issue with the processor not completing initialization. If it starts into POST and the first step fails you get a long beep to say the memory is having an issue. No beep means you aren't getting that far.

FishfingersNZ

Thanks billsey, very informative. Same issue if attempted power up via battery alone, docking station or with power supply connected. Was hoping it would be just a dead LCD. So somehow I need to trace from the power switch. Do you think it's likely to be a dead mo/bo? Fan does jump on doing a battery reset.