RND2000 Duo v1 - lockup after boot - OS partition full?

(NB: reposting since it appears my original post never got published for some reason...? https://community.netgear.com/t5/Using-your-ReadyNAS/RND2000-Duo-v1-lockup-after-boot-OS-partition-full/td-p/1447681)

Hello again forum!

TL;DR - think my OS partition is full. go to *** END STORY *** if you don't want to read my treatise 

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So my ReadyNAS has decided to stop working for me. Not sure when exactly it stopped working - we weren't home for the last week - but upon returning I found a NAS that I couldn't access (Network Shares, FrontView, RAIDar, ping, etc).

After troubleshooting networking issues, I attempted to power down the device via the power button to no avail. Left with no other option, I pulled the power (not much different to losing power, so...). Upon reconnection and powering up, I was overjoyed to see an email from my nas advising of the improper shutdown and a commencing RAID sync. Huzzah!

I then however find that whilst I was talking to it (and it me), it stopped responding (and access via the aforementioned methods ceases to work).

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NAS Details (sketchy as I haven't looked recently and I don't want to power it up just to get latest info)

Hardware: NETGEAR ReadyNAS Duo v1

Drives: 2 x 2TB WD RED WD20EFRX, RAID 1

Radiator Version: 4.1.15 (I think... it's been emailing me all the time to update to 4.1.16)

PC Details

Windows 10 Laptop, typically accessing via wirless (can jack in if required)

After a bit of Googling, I find a few posts that give me the impression that it is a full OS partition.

With this knowledge in hand, I'm now looking at fixing the issue but would like to have all the information at hand before I commence and potentiall brick my NAS. I do know my way around PCs, although am not familiar with *nix commands (have played with it a tiny bit many years a go on Red Hat GNOME & KDE, and I do have an Ubunto Live CD here somewhere...).

Sources:

• https://community.netgear.com/t5/Using-your-ReadyNAS/ReadyNAS-Duo-v1-Full-OS-Partition/td-p/1136435
• http://geertvanhorrik.com/2015/09/29/fix-readynas-frontview-broken-or-no-logs-exist-without-losing-d...
• https://onlyblueatwork.wordpress.com/2012/12/04/netgear-readynas-access-recovery/
• http://netgear.nas-central.org/wiki/TechSupportMode

Proposed process:

• Remove Disk 2 (for data safety)
• Boot NAS to Tech Support Mode (power button 20 seconds?)
• SSH (Putty) to NAS - un: root / pw: infr8ntdebug
• Mount partition:

# /bin/start_raid.sh
# mount /dev/hdc1 /sysroot

• Confirm full partition:

# /sysroot/bin/df -h
# /sysroot/bin/df -i
# /sysroot/usr/bin/du -csh /sysroot/var/*
# /sysroot/usr/bin/du -csh /sysroot/var/log/*

• Copy massive log/s to data parition as appropriate

# cp /sysroot/var/log/frontview/error.log   /???/backup_frontview_error.log
(change /frontview/error.log as appropriate, not sure on destination file/location?)

• Empty log/s as required:

# echo > /sysroot/var/log/frontview/error.log
(change /frontview/error.log as appropriate)

• Come back here when it doesn't work