Advice wanted regarding sending computer away for repair / replacement

As I have not found a business or anyone willing to replace the emmc drive in my 2-in--1 Tablet PC I am very probably going to have to send it from the UK to USA for replacement / repair, under warranty. I am very much in need of advice regarding this unfamiliar and unwelcome action.

For example, if possible should I format the C drive? And before doing this should I backup all or some of it to an external drive first, or is it likely this will copy the faults in the drive?

Secondly, with regard to the imminent Creators update should I try to install this before sending the machine back, or should I try to send it back before the (compulsory) update arrives?

I may well be able to carry out these procedures because I understand (although the machine is not in my hands at present) it is still usable for many activities, despite the faulty drive, which is however causing more than a dozen malfunctions, like being unable to download / update Store apps, or set a PIN code for signing in, or use links in Mail, etc.

If the problem with the drive is just app/Windows related you could try a repair install via the media creation tool, this will not remove files or programs but will repair Windows.
Information here: https://www.tenforums.com/tutorials/16397-repair-install-windows-10-place-upgrade.html

Always backup your data before sending your computer away. Local or out of country.

I would not wait for updates as there is no guarantee that they will re-install it for you anyway.

I also would not wipe the unit as that may take away clues as to what is going wrong with your system.

If you have any sensitive info like account #'s or passwords, delete them. 

Thanks for the advice The repair shop could not get the repair install to download, or a number of other things to work. After a scan taking several hours he concluded that the emmc was damaged somehow --- he found many faults on the drive, though my scanning apps do not report any but they are no doubt far less sophisticated than his. One thing which puzzles me is this. My machine is dual boot. The Android OS is working perfectly, it is only in Windows 10 that i get the problems. I have little tech knoweledge but that makes me wonder if it really is the drive hardware at fault as I would have thought it would affect both OS?

What is the make and model of the 2 in 1? If Android and Windows are on the same drive then I doubt the drive is bad if Android runs well.