Not sure I would trust the Microsoft with the return, unless I was getting a new SB3. Not installing firmware or updates will eventually cause issues for support and compatibility. I would also recommend apply the latest updates. I have done this since WIn10 on SB and PC with very little issues. Plus you will need update for Microsoft Defender A/V unless you have a third party.
Mines is okay since the 15/6 update, I will perhaps run a game for 1 day full to see how i get on. No loss of GPU so far from suspend/resume.
You could try the Win10 update troubleshooter, or some of the options below.
How to Fix Windows 10 Update Stuck on Checking for Updates Issue (guidingtech.com)