I've made good progress but could use a little more help.
I'm doing this on a Mac. For anyone else who only has access to a Mac, a couple of notes which might save you trouble.
1) The steps to prepare the nk.nb0 and USB flash drive files have to be done on Windows. I tried setting up VMWare Fusion 13 on an M1 MacBook Pro with a beta of Windows 11 for ARM, but too much stuff is broken. I ended up using Fusion 13 with Windows 11 on an older Intel MacBook Pro which worked fine.
2) I had trouble uploading the nk.nb0 file from TeraTerm via Fusion. It would just stop transferring at random points unexpectedly. I ended up copying nk.nb0 to the Mac side. CoolTerm usually works okay for me, but didn't have ymodem options and whatever it was using would transfer the file but then loady would just time out. I ended up installing minicom via HomeBrew. That has a ymodem option but would just do nothing when initiating the transfer. I had to install lrzsz via HomeBrew as well and configure minicom to use lsb and lrb instead of sb and rb respectively. With that setup the file transferred okay and the scope booted!
Help wanted:The USB drive was prepped as the instructions advised with 02.35 firmware. The drive mounted on the scope okay. I selected the CAB file to update and a dialog popped up to confirm. It seemed to start to kick off the process but then the USB drive would disconnect and nothing else would happen. Trying again and again had the same results.
I checked the currently installed firmware which is 02.36. So I tried copying over 02.37 CAB from the thread and the 02.65 CAB (renamed from .ksx) from Keysight's site. Both of those had the same behavior as 02.35. Rebooting the scope regressed to the original symptom.
So, is this a known issue too? Am I possibly doing something wrong? Maybe try a different USB stick?