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Windows Update is a torture chamber for seldom-used PCs
(www.theregister.com)
This is a most excellent place for technology news and articles.
Dell has their own instructions on making a bootable usb for bios updates:
https://www.dell.com/support/kbdoc/en-us/000145519/how-to-create-a-bootable-usb-flash-drive-using-dell-diagnostic-deployment-package-dddp
Do it the hard way or the easy way. Oh and good luck with a drive update.