04-20-2016 11:02 AM
I was working on a client's HP 15 Touchscreen and needed to boot a flash drive to perform a virus scan. It originally had Windows 8.1 instaled but had been force-upgraded to Windows 10.
When I enabled Legacy Support it automagically disabled Secure Boot. I set the UEFI boot order to USB, OSD then HDD. I set the Legacy boot order to USB, OSD then HDD. Saved and exited.
Laptop restarted and stopped dead, nothing but a gray screen. Fan runs but HDD is silent. Nothing on the screen, not even a blinking cursor. Power off, pull battery, disconnect AC, drain the capacitors, attach AC and boot. Same result.
Power off/on and tap ESC, same result. Repeat but tap F10, same result. Connect external monitor, no video. Recover BIOS and boots perfectly from HDD, still no Legacy support.
Tried just disabling Secure Boot only but it automagically enabled Legacy, and disabling Legacy automagically enabled Secure Boot.
I've scoured the internet and this forum. Saw one topic with exacly the same problem but with no resolution. I no longer have the laptop so cannot give more info or do further tests.
Does anyone know why enabling Legacy and disabling Secure Boot would cause this? Need an answer 'cuz I'm pretty sure this is going to be a problem in the near-future. Thanks!