Good news... I spend the afternoon testing it and the USB to AV converter works!!
When the AV unit starts up, it displays "xanavi>" and then you can type a command.
Here are the "ver" (version) and "hdd 1 1" command results:
and a list of all the commands that can be used at the console:
btm bcsp xrbt xroem lpavm cwsh cws teld gpshist snr tms xrinit gid dsh hdlxmw hmixmw hvac pmgrdiagn pmgrcamera mgrvcan candiag mgrcan hdlmtr hdltmcair hdltmcsend hdltmc trfe trfs hif refdbg rdset rprt rdbg ipverr navistsreset navistsset ipvreset ipvset self hdlmfd mfd xrdnk aview hmi avm sdl xrcnf xmcu ir xgc1 verall imng wel sql mdc mal xrnt lang dat hdlm atv devs drvs fds oms ldset dor vm onmap trf map rcv vdb aps as asss se ss etcs camera switch rgdv rpf dspctl tol rif hwn rgd rgdc hdm dspset imtest usbrb tel mum vfi lvc hms menu mtrif mtrsd tcp tce tc clw sns xrpo tla hnw dsp obj svr usbmgr hdd ucm acl mgrweb mgrweb adpbtd adp gdicscpu pdicusart sys disc aux dvd audio mec bpss dusa dus ls rm xtp xgpsd xclw xgte xgts xcpl xste xsts xsrad xrsn xrf xfver xrde xrspn xrmfc xrd xrsfl xrmc xrpc cap mgl font xgl mgrbt pmgrestab echo dlp xplsd xgrad iodspi pldck lte lt bpb bps bpc bpa bpp bp pld wdd fcopy call swm mgrmcan acm iodpt iomsgio pmgrspd pmgrgps dspst dspsd pmgradc pdictmu pdicspd pdicscif pdichcan pdicadc i2c iomsgi mcan docan ioltimer ioltime iolring iollist iodev mqsa mqs cs exc exd ex ms d m spyStop spy dbgHelp tt e mRegs l ti so s cret c bdall bd b xcv sca sc prc pw ee es ver oss sas sd promd proms cf co osee oses tshow tr ts i
Next weekend I will add the LCD nav screen, nav buttons and radio/AC buttons to the setup to help with testing.
Oh, one last thing.
During the summer, I used an app to re-program a different AV unit, and it got bricked when the app crashed. *BUT* as it turns out, it isn't bricked, but has a bad configuration that turned off CAN bus communications.
I was able to use the console to send the "restore to factory defaults" and I suspect I can now reprogram it. For a while I thought I just wasted $100.
That's all for now!