I recently purchased a refurbished Latitude E5470 i6300u which came loaded with Windows 7. I wanted to upgrade to Windows 10, so initially I downloaded an ISO for the latest Windows 10 Creator version and installed it fully wiping the hard drive. I let it pull down all the necessary drivers from Windows Update. Everything seemed to go well, except I found that when the machine went into sleep mode neither the keyboard or touch pad worked.
I downloaded the recovery disk from Dell for Windows 10 and installed that (older) version of Windows 10. Prevented Windows from connecting to the internet and installed all of the drivers from Dell's site. Same results, no response from the keyboard or touch pad upon waking from sleep.
I do notice that keys like the brightness buttons still work, so the BIOS is still communicating with the keyboard. Windows is just ignoring it. If I connect an external USB mouse and keyboard, they work so Windows isn't locked up either, it's just not accepting input from the internal keyboard and trackpad.
I've tried booting into troubleshooting mode only loading the basics, same thing. There are no errors in the system log and looking at device manager while the touchpad and keyboard and not responding looks normal.
It DOES come back from sleep just fine in Windows 7 or of I load Linux on the machine. I am out of ideas. It seems the only solution is don't use Windows 10 or block sleep mode in the BIOS.