This morning I saw that we now have the new Victron firmware available (I think 507), and as always I went through the firmware update motions.
This time however it got stuck on 67% and that was it.
After waiting a little while, it reported “Error, please try again” and that was it. The inverter is not switching on with all Led’s flashing when I tried to do it manually 
So now I am in pursue for the cable, but I am not even sure if it will work as the inverter is not coming on at all
Help 
Updating firmware is like buying new underwear. I only do it when the old ones stop doing the job…
All LEDs flashing means “firmware corrupt”. Which is exactly the sort of thing you’d expect in this situation, although I find that I get the no-lights-at-all or some-random-pattern one more often.
You can still reflash it with the mk3-usb cable. And no worries, I’ve deliberately firmware-flash-bricked a Multi many times in testing. They come right out with the mk3-usb.
Let me ask a few questions to see if there is a faster option here. Back in a minute… or ten.
Flip side to that, some have to try it first to let the developers know of bugs so that the rest of us can happily do it later with no drama.
I’ve had my share of “o donner”. Still, I tread where others fear to go.
Also why I thought it prudent to have a MK3 onsite, having bought it for cents on the rand on Gumtree. 
EDIT: The only software I have given up on, is HomeAssistant. Moved all the “mission critical” to NodeRED on the Cerbo. Gave up after about ±5 times of having to redo it all after an upgrade, with backups not even working as “advertised”.
Those people that like to be first like TTT is called cowboys (normally jumping in without caution). It’s also the reason I use the icon in my profile.
99% of the time it can be fixed. 
Also why I thought it prudent to have a MK3 onsite
Well, that is just it. I went to the solar store here in the neighbourhood and got the MK3 interface. Without it, one can’t restore the system.
Anyway, even though it was flashing like Christmas three - I plugged the interface in and saw it on my computer. Force updated it (password “zzz” was needed), and voila 
Back to square one, lickily I know the details of my setup, so it jus took configuring all back - 20mins, all up an running
Now at least I have the cable, incase anyone around JHB / Randburg gets stuck, happy to help out 
YES!!!
Once had an MP so old, it could not update.
MK3 cable, voila. Inverter is back in operation going forward.
Victron knows how to develop software.
Like Plan A, B, C … Z,
then a, b, c … z,
then AA, BB, CC … ZZ,
or aa, bb,cc … zz.
I just got the answer I needed, which is that it CAN be updated without an mk3-usb (from the commandline, if you know what you are doing), but since you have come right already, it means I don’t have to do that anymore
And now you have the cable.
As I said … Victron knows how to develop software.
Listen, for those who don’t know me. I’m not “Victron be-k_k”, no.
It is just they seem to have customer support and care down pat. Sometimes even 24/7 depending on how much effort one is prepared to put in … someone will help, even if it is not official Victron support. A culture they created internationally among Victron users, installers.
Nothing makes me run for the hills faster than a company that ignores customers requesting some help.
Especially when the customer keeps their cool sitting calmly waiting in the dark for assistance to be rendered.
Command line sounds interesting option, but surely one needs to be connected to the unit somehow? 
This MK3 interface seems like some sort of serial (rs232 or rs485 or ?) to ethernet 
You root the Cerbo, and once you are logged into the Cerbo you can access the mk3 chip built into every GX device and use that to flash the firmware, using a command called vbdup. Everything can be flashed from the commandline, and whenever you use VRM to do such updates those tools are called in the background anyway.
As long as you leave the Multi in the bootloader (ie don’t turn it off and back on), and you don’t reboot the GX device, you also can just flash it again from VRM.
But explaining to a customer who isn’t highly proficient in doing such things, the entire process… well, that takes time. And the trouble with us software people is, we are totally incapable of thinking of all the possible ways people can mess things up. So as a result, we prefer to do it ourselves
No, not really. It’s a USB-serial chip to start with (good old FTDi), and then on the output of that it speaks to a microcontroller which in turn has a RS485 interface (which is what VE.Bus is). But because this is a bus where timing-sensitive things happen, you are not allowed to interface with it directly.
By analogy, in cars you will find multiple CAN-buses, some related to the security system, some related to entertainment, some for engine/drivetrain management, etc. And in most cars, you are not allowed to connect directly. You have a connection to a gateway module (eg in BMW land it is called the ZGM, the central gateway module, and it is often built into the BCM, the body control module), and that ensures that you don’t break things on busses where you shouldn’t be.
Same here. Mk3 makes sure you don’t break things in parallel/3-phase systems where critical things are flying over the wire all the time.
Once it failed, that is exactly the first thing I did - like with an old windows laptop - switch it off and on 
Now many old windows laptops start working afterwards 