Can no longer get to web interface after firmware update 6.5.2

Hi all,
I’ve owned a ReadyNAS 102 since 2015 but not used it for quite some time. This week I’ve powered it back on and it was using firmware version 6.2.4 (I think). I backed up the data to an external device and attempted to perform the automatic update. This said it was installing 6.5.2 but on each reboot it was still showing the old firmware version.

I then tried to perform a manual firmware update by downloading the 6.5.2 file and the same result:
https://kb.netgear.com/31116/ReadyNAS-OS-Version-6-5-2

At this point the NAS is still functional and all services seemed to be working including the web interface but it will not upgrade the firmware.

I then tried to perform a “factory default” to see if this would resolve the issue but after this step the device boots with the power light flashing and doesn’t have a web interface. Performing a port scan against it can see that only telnet port 23 is open:
https://kb.netgear.com/22892/How-do-I-access-the-boot-menu-on-my-ReadyNAS-102-202-212-or-312

RAIDar has the status as “Corrupt Root”. So I then try to perform the OS reinstall. This gives me the same result. At this point device still shows as the old firmware version.

I do a little digging and find this article:
https://community.netgear.com/t5/Using-your-ReadyNAS-in-Business/Ready-NAS-102-in-accessible-corrupt-root/td-p/1062056

Following the process and perform the USB firmware update and this seems to work as now the RADar app shows firmware 6.5.2. The problem is it still shows as “Corrupt Root” and no web interface to the device.

I’ve tried all the above with and without the disks in the device and get the same results. When the disks are in on the reboot RAIDar says “disks are dirty and need formatting” but this doesn’t seem to resolve even if left for 4-6 hours.

Anyone else got any advice to resolve this?