A few weeks ago I came back from a holiday, having left the Mark II running in my absense.
The fans were running, but the screen was black (grey, because functional).
I’ve attempted starting without thumb drive and with, but both give the same result: no response other than a running fan.
Is something broken? How best to find out?
I do not have a working alternative OS yet, because I did not check the size of the image (7Gb) before buying thumb drives… Anyone want 4Gb thumb drives? 
Because MycroftAI’s backend services are abandoned, and because neither Neon nor OVOS has the access (or the desire) to maintain them, I wouldn’t be surprised if every Dinkum and Classic Core instance on Earth just stopped working, but that wouldn’t result in a grey screen.
Some of the thumb drives they shipped have been faulty, or it’s just possible that Dinkum did indeed put itself in an unrecoverable state.
Thing is, for reasons which have probably made themselves apparent by now, OVOS’ official position on Dinkum support is “please don’t use Dinkum”
Alright.
I’ll consider whether to use OVOS or NeonOS, but since I have two devices, I may as well get to using both…
I hope it’s as you suggest, and it’s just Dinkum having imploded.
Thank you for your reply.
I thought I was clever and just download the image…
But I’ll just go through the process of getting a thumb after all.
Thank you for your reply.
Hi @MyValdr , Clary here from Neon AI, I am able to send you a replacement Dinkum USB drive along with our OS to try. I just need your address, either through an order on our Square site, an email to clary@neon.ai, or a private message on here. If you’re outside the US I need a phone number and email as well to go on the shipping form.
Welcome to the community, I’m glad to hear you’ve been enjoying your Mark IIs!
USB drives, especially the Kingston brand shipped with the Mark II, simply aren’t able to operate long term under the constant read/write cycles that the Dinkum OS uses. You’ll see better longevity and performance for that or any similar OS using an SSD drive.
If you decide to put an order in on Square, just include a note telling me you’re the person who wanted the replacement Dinkum drive, I’d be happy to send you a new Dinkum drive along with a Neon OS SSD. You can use coupon code MycroftForumReader to get $10 off an SSD.
To be clear though, no obligation to order anything from us - if you’d just like me to replace your Dinkum USB I can do that from a small stash of them that I have, at no charge, as part of the support we’re providing to the Mycroft community. It’s really a Mycroft warranty claim, but it would be silly to have you email Mycroft support just so I could answer you from there.
Do you mount directories frequently written to as tmpfs’s?
-Mike Mac
We can’t speak much to Dinkum’s performance problems. NeonOS and OVOS use tmpfs. Dinkum is the result of an experiment MycroftAI conducted in outsourcing the “Linux appliance” part. The only thing we can say with confidence about Dinkum’s system layer is that it’s weird.
Good afternoon @NeonClary
Let me digest your e-mail while drinking some tea…
If it is indeed the crappiness of the USB, then I do want to claim warranty.
I haven’t pledged allegiance to Dinkum, and I would like to try Neon and OvOS… I did get two Mark IIs for a reason…
Since I am indeed outside of the USA, let me send you that e-mail, so I can smack a few flies in one whallop…
Thank you for your support.
Happy to help! 
Your package will be on the way soon.
*I think I ought to specify for any others reading, that I don’t actually know that the USBs are covered under the warranty. Most folks have opted to upgrade rather than replace them with the same thing, so I’ve just been replacing them for they few who request it because that seemed like the right thing to do.