BLUF: Check Secure Boot and UEFI/CSM/Legacy
This goes for hardware w/UEFI - regardless of OS
I chanced upon this in a Win7 system that had been downgraded from Win8
While updating the drivers I updated the UEFI - and the system refused to boot.
We tried everything possible to get it to boot and nothing worked.
The downgrade had wiped the recovery partition, so we couldn't even try to recover it to Win8
While browsing around inside the UEFI settings I noticed that Secure Boot was enabled.
I didn't think you could do that with Win7? And then the obvious slapped me upside the head!
I disabled Secure Boot and set the UEFI to CSM (Legacy) and viola! It booted!!!
What happened here was that the UEFI reverted to default values when it was updated.
And Win7 was installed without it - so it couldn't find the OS in order to boot it.
This goes for hardware w/UEFI - regardless of OS
I chanced upon this in a Win7 system that had been downgraded from Win8
While updating the drivers I updated the UEFI - and the system refused to boot.
We tried everything possible to get it to boot and nothing worked.
The downgrade had wiped the recovery partition, so we couldn't even try to recover it to Win8
While browsing around inside the UEFI settings I noticed that Secure Boot was enabled.
I didn't think you could do that with Win7? And then the obvious slapped me upside the head!
I disabled Secure Boot and set the UEFI to CSM (Legacy) and viola! It booted!!!
What happened here was that the UEFI reverted to default values when it was updated.
And Win7 was installed without it - so it couldn't find the OS in order to boot it.