Re-image a Series 3 TivoHD

I'm a bit lost in all of the stuff posted here. Here's my situation -- I have a TivoHD Series 3 that is largely broken because Tivo accidentally upgraded it to a bogus software version. They are going to charge me a few hundred dollars to replace it.

What I'd like to do is completely re-image the drive to a "correct" version of the software, so that I can get something working again. The unit has lifetime service. Specifically, it is a TCD652160.

What's the best/shortest/easiest path?...

Re-image a Series 3 TivoHD

Re-image a Series 3 TivoHD