Tried upgrading to the latest beta, the A4 was stuck in “Erasing Flash” for a while, like a dummy I restarted it.
Now it wont let me start it up at all.
No Factory Reset,
No Empty Reset,
No OS Upgrade.
What do I do?
The upgrade README says:
[ol]
[li]do not turn the power off during the upgrade. [/li]
[/ol]
Did you try holding in the [function] button while turning the device on?
After this you can hit [Trig 4] to enter OS UPGRADE mode.
I have no idea if that works if the flash content is corrupted, but would guess that’s what it’s there for.
I know all of that.
I screwed that up.
So now what.
Log a support ticket. 
damn… sorry for you bro.
Oh man… I hope tehre is a way to reset the damn thing, must be. Could happen to anybody - power outage etc
Yeah, I got excited and stopped thinking carefully.
In my mind when I hit the switch I was just like, “start over.”
It all happened so fast.
I would be interested if it’s possible to fix it not by Elektron but by someone with engineering background using USB programmer and instructions from Elektron support.
Reflashing a chip takes less then a few minutes.
Btw, I always do upgrades under the UPS backup system, just in case.
Support got back to me reminding me that I needed to use Midi to Upgrade the OS through the early Start Up Menu.
All is well now!