Question I've made a mess trying to update Windows 7 to 10 with a portable hard-drive left plugged in - black screen, no POST, no BIOS

Aug 20, 2020
Hi everyone.

I've recently been looking at getting an old (5ish year) gaming PC up and running again now that I had some time during lockdown, and I've run into some issues trying to update from windows 7 to 10 after leaving a portable hard drive plugged in .

I wanted to update the OS to Windows 10 using the desktop update tool. Unfortunately, after starting the update I realised that I'd started it while leaving my portable hard drive plugged in. After I left it to do its thing, it tried to restart and I was left with a blank screen.

Any attempt to power it up after this has led to a black screen and I haven't been able to get it to POST at all. One restart where the hard drive was plugged in managed to get to the splash screen as I didn't have time to plug in a keyboard, before hang boot-ing (white screen, blinking cursor from trying to boot from the hard drive). After this, I haven't had any luck getting to POST or bios at all, with or without the portable hard drive plugged in. I tried jumping the CMOS, leaving the PC to discharge unplugged over night and most other home tricks, and currently have left it back with my local repair shop who are doing their best to get it working again.

Having just read through Darkbreeze's very helpful "How to do a CLEAN installation of Windows 10" guide, I saw this:

Before you begin the installation, whether now or after you create your installation media, it is of utmost importance that you disconnect ALL system attached storage drives EXCEPT for the target drive. This is important because we've seen instances where the system has decided to install one or more of the created partitions including the boot, EFI or recovery partitions on secondary drives making it impossible to boot (Or recover) Windows if that secondary drive is removed.

I'm pretty sure that this is where I've made my serious mistake, and I'd really appreciate some help with getting it to POST if possible if there is a simple solution that I'm missing. I'm happy to boot from a USB with Windows recovery media, clean install windows 10 and wipe the system, I just need to get to BIOS!

I'm sorry if this question has been answered before, I just haven't found anything that worked while I was troubleshooting. The PC is currently sitting like a brick in my local repair shop, so anything that I can pass over to them to hopefully sort this issue would be very much appreciated.

Happy to provide any more information needed. Thanks everyone.



Mar 16, 2013
While having only one drive connected during this process is strongly recommended, having more than one should not result in the issues you are seeing.
Specifically, it would not have modified the BIOS.

Given no actual hardware issues, a clean install as per the link from Darkbreeze should work.