The original thread (https://www.dell.com/community/Networking-Internet-Bluetooth/KM717-bluetooth-keyboard-won-t-go-into-pairing-mode/td-p/7428288) seems to be too old to reply to, but if anyone is still having these issues and wants to update their KM717 or MK717 keyboard firmware or do a factory reset, there is a way to do it via an Android app.  I didn't have the pairing issue, but other issues (missed key presses) and ran this to update my firmware and it seems to have fixed my problem.  You can find the app here: https://play.google.com/store/apps/details?id=com.hstnet.dellwk717dfu.  Hope this helps someone with their keyboard.

Harry