[SOLVED] Computer cannot boot & red boot device LED is on ?

[PCUser360]

Motherboard :Z97-A Asus
OS: Windows 10 64bit
Graphics Intel on board
Nvidia Dicrete GPU

The computer was working fine this morning. Shut down no problem.
In the afternoon, I replaced the CMOS battery then it cannot boot past red LED boot device stage. Needless to say I cannot get into BIOS.

Assuming the new battery was faulty, I replaced it by a second new battery. It still would not boot past the red LED boot device stage. Swapped back in the old battery also did not help.

The boot LED sequence went though CPU, RAM, video, RAM, video, then got stuck on the boot device stage.

I read on here that one should disconnect all SATA & power cables to all the optical and HDDs and reboot. It still got stuck on boot device?
With no drive connected, should it not be able to get past the boot device stage and go into BIOS?

Also took out CMOS battery and unplugged from power for 30minutes.

I am not sure what else to try.

Please help? Thanks!

 

[PCUser360]

Ok I solved this myself. I ended up trying to boot up the computer by plugging in a USB stick, a USB hard disk drive hoping the presence of an external drive would trigger something during boot. The computer still refused to get past the Boot Device LED stage in both cases. After that I booted the computer again with neither plugged in and it actually got past the Boot Device LED stage and into Windows finally.
After that the computer does not seem to have any further problem.

So if you have a similar problem, try plugging some external drives in before booting up. Maybe it will trigger something for you too.
Good luck!