[SOLVED] ReadyNAS Ultra 6 Plus updating FW - hung up

[Powersup]

I got my new Ultra 6 Plus with Raidiator 4.2.15 installed. I put in my 3 2TB Samsungs HDDs from my prior Ultra 6Plus and everthing was fine. After that I downloaded the 4.2.19-T4, started the updating process with frontview and reboot the device and the display said "booting, updating fw" for almost 30 minutes. I tried the "OS reinstall"-option from the boot menu, but the same happened.
In the first minutes after starting the NAS RAIDar can see it and says "updating". After a couple of minutes RAIDar can't find the device anymore:(.

Does anybody know something about this issue?

[Powersup]

The ReadyNAS Support solved the problem. A technician logged in via telnet and reinstalled and downgraded the OS to 4.2.17. After that I installed 4.2.19-T4 again and it worked - as it should - fine.