POST Screen

Windows won't be changing anything in that regard, it has to be a setting you changed like fast boot in the bios or something it could be called something else.

This image was for a different topic so its slightly out of context in some regard, disregard most of it but it still relays the sequence. The post screen happens in the green area before windows loads and windows won't be effecting that area of the loading.

When you get to the first blue area then this is when windows is in control so basically when you see the windows logo.

if nothing comes up when you press the button to turn on the pc and then it goes straight to the windows logo basically then that would suggest fast boot. Although The computer should display something before the windows logo because ethically the user needs to know at glance that the computer is working. Maybe there is another issues at hand hard to say.

Fast boot in the bios would usually mean showing the manufactures logo instead of the full post diagnostics output. So it does not make sense here. The blue screen you describe could be because its loading to fast or something hard to say really.

Also older laptop so i don't think this would be the case, maybe there is rom issue like the actual flash etc.

Sounds more like corrupted bios imo, potentially a case that the OP is not stating everything at play compunding effect because unconscious unknowing. Using software solution to try flash the bios. Potentially other factors that we are unsure about as third parties.

blank blue screen when the pc turns on with no image and then cannot enter bios sounds like a corrupt bios, cannot flash the bios from software solution when in OS it all adds up. Id say at this point be happy that the computer turns on and functions.

The whole point of post is two things its supposed to pass the computer through tests PowerOnSelfTest and two its supposed to display in a visual sense that the display is outputting to the user so if nothing shows up before the windows logo then that is contrary to the point of POST. its pre boot side of the coin so before windows is even loaded.

It does not make sense really because it goes against the whole paradigm if it was me i would just be happy that computer works. Try the cmoss reset because that could bring it back but its not looking good in that regard.

Could be benign OP going to come in next minutes saying something else and that they fixed it from far over there.