What did Sonos support say when you called them? What charger are you using when you plug in the USB C directly, is it the Sonos charger, or another? 

Try this reset:

After the unit has been charging for a while, remove from charger, press and hold the power button for 15 seconds. If your finger slips off the button, restart the interval. If the unit starts, I suggest that you continue charging to 100%. You can listen to music while you charge.

Note that this is not a Factory Reset. No settings will be lost.

@Airgetlam I have not yet called their support number. I had been using the wireless charging pad that came with the speaker. When plugging in via USBC, I’m using a big, fat Anker brick and a good Anker, braided cable.

@buzz Thanks for the suggestion. I tried it a couple of times, but no noticeable changes unfortunately. 

When having charging issues, I try to stay away from Qi charging. What power ratings (voltage and amperage) on that Anker brick? Physical size has little to due with capability. 

Up to 100W

https://www.amazon.com/gp/product/B09W2N774C/

Odd that they don’t quote amperage, but yea, I’d agree, that should be sufficient. 

For now, stay away from the Qi charging until you can get it figured out. And I’d recommend following the posts made by @buzz closely. 

Hi @Sneake 

Welcome to the Sonos Community!

If @buzz’s suggestion did not help, I recommend you get in touch with our technical support team who have tools at their disposal that will allow them to give you advice specific to your Sonos system and what it reports - you may simply have a faulty Roam, in which case we will look into your replacement options.

I hope this helps.

Mine is dead too. and sonos just said that they can offer 30% discount.
But I tried to replace battery. And bought new battery on Ali Express
Due to waterproof, It use kind lot of sticky tape and hard to tear down (Seems not to be replaced)
With teardown guide, It tooks 1hour to replace battery. And it brought back to life with some compromised integrity
If you're willing to take a risk try to replace a battery.
For me it’s way better then throw it away

It is indeed a faillure of the battery, I don’t know if its a Lithium or Nmih. 

Terribly disappointed that Sonos has not thought about how you can easily replace this battery, especially for a portable product in this price range. What a disappointment in Sonos.

Another made in China product from them.