Downgrading Surface Laptop 3 from Windows 11 Pro to Windows 10 Pro

[SurfaceRefugee]

Hello. I have a Microsoft Surface Laptop 3 (i7, 16Gb, 1Tb, 13") that was recently reset to a new install of Windows 11 Pro. I want to use Windows 10 Pro instead. I am having difficulty getting the "downgrade" to work. Here is what I have tried to do.

I have USB ISOs of both W10 and W11. I also have a Macrium Reflect image of the working W11 installation, so it can be restored. I set the device to restart from USB. I restart.

With the W10 USB ISO inserted, the installation process starts just as expected. BUT: the device is nonresponsive to input from its keyboard, touchpad, and touchscreen. (Both worked fine under W11. That is not the issue.) I power down the device by holding the power key.

I plug in a USB hub with a kb and trackball attached. I start the device. The attached kb/tb work fine, but the native inputs still get no response. I complete the W10 set up (bypassing the MS account and using only a local account) and finally get into W10. The native inputs still do not work. I reboot. Same thing.

SO: I set the device to boot into the Macrium Reflect environment, restarted it, successfully restored the W11 system image (which is stored on another partition of this 1Tb SSD.)

After being restored, W11 appears to be working perfectly. So no harm was done. BUT: I don't want to use W11! For reasons I'd be glad to go into. But for now: Any idea why the W10 install process would not respond to native input devices? Even after W10 is fully set up it still didn't see input from its own kb and touchpad and touchscreen? But W11 works perfectly.

I have experienced something like this before with (I think it was) a Surface Laptop 2, but after using the USB kb to get through the setup, everything worked fine. I own a few other Surfaces all running W10 Pro.

The Surface Laptop 3 when new shipped with W10. I think the firmware might have been upgraded when the device was upgraded to W11. Could that be the issue? Is it possible to downgrade a firmware update?

All suggestions appreciated.

Thank you!

 

[SurfaceRefugee]

An update.

I was able to get Win 10 Pro working on the device good as new! It didn't actually take much.

I restored the system image I made of the new Win 10 install where the kb, touchpad, and touchscreen didn't work, and I had to use a usb kb. At the time, WU told me there were no more updates, and I always double check that at least twice, before postponing updates for as long as I can. It was at that point that I took the image of W10, and then reverted back to Win 11, where the native inputs worked fine.

But this time, after I restored Win 10 and ran WU again, it found a ton more updates it hadn't found just 3 days earlier. As they installed, the inputs started waking up. When it was done, all was working as expected. Which is what I expected the first time around. Odd how WU would find such critical updates just a couple of days after saying there were none, while leaving the machine inoperable.