Refurbished XPS 13 2-in-1 9365 - Multiple Issues, Please Help

Hi there,

I am experiencing multiple issues, most of which have been described in other threads but either they aren't resolved or the fixes haven't worked for me. Problems include:

1. NO audio (either through speakers or headphones)
2. a crazy-loud, exploding noise that happens intermittently even when I am not using the laptop
3. the laptop fails to recognise external hard drives (two different ones that work on other PCs), indicating possible issues with the USB-C ports and
4. when I start up or re-start it gets stuck on the black screen with the Dell logo but nothing loads (no circling dots at the bottom indicating it is loading up) and you need to power off and restart a second time.

I can usually replicate my exploding noise by trying to play a video/audio file.

The laptop was working fine until about 6 weeks ago. One evening I was using it (it was plugged into external power) when it suddenly came up with a warning about low battery (which couldn't have been correct because my laptop is constantly plugged in at my desk and doesn't leave it), then a second later the screen suddenly went black and the machine shut down. The next day I noticed the audio issues and then the other issues slowly started occurring.

Dell did various remote assist sessions and had conflicting opinions on whether it was a software or hardware problem. Nothing they did or suggested worked. I have tried updating the Realtek drivers, updating the Intel chipset (?), updating the BIOS, updating and rolling back Windows updates, re-installing the latest version of Windows 10 and even re-formatting the HD but nothing has helped.

The laptop is no longer under warranty. My thoughts are that a motherboard replacement may work but many people have discussed how motherboard and/or speaker replacements have failed to solve their audio issues.

Have I been  into buying a lemon of a machine that is fatally flawed?

Can anyone from Dell please let me know what they think it is? I am desperate and my faith in this company and their products is dwindling fast. (I previously have bought 2 laptops new from Dell and never had any issues.)