SOLVED - Rigol MSO5000 firmware reset without UI?

[Harvs]

I've got a Rigol MSO5000 that today decided to fail on start halfway through the day. Gets to the UI, and I can get a single button push in before the UI locks up. I haven't used the ethernet before, but assuming it would be DHCP by default, it doesn't show up in an ip scan.

At a guess it would seem like a file has been corrupted, but hard to be sure? Seems like it locks up as it's finalising the boot process.

It's hacked and I have the /rigol/data folder backed up.  It's not very old, so would normally be a warranty job, but it's pretty obvious it has a whole lot of stuff enabled that I didn't buy keys for.

So anyway is there a way to reset or reload the firmware without the normal menu access and without opening the case?  Or is it a matter of cracking it open to get to the uart?

Sorry if there's something I've missed with my searching and this has already be answered somewhere.

[Harvs]

Found it, I knew it would be in there somewhere!
https://www.eevblog.com/forum/testgear/hacking-the-rigol-mso5000-series-oscilloscopes/msg2250807/#msg2250807

Thanks to everyone who contributes to this great wealth of info.  Scopes all good again.