elverhunter

Hi everyone,
I been reading lots post in this site for 2-3 yrs
and thank you very much for very good informations

I have 2009 ML550 and it has comand unit problem
It all started about 2 years ago
My battery drained one day and jump started
then comand unit lost all sound and nav
next day took it to dealer and comand unit was working again
Dealer guy(Not technician) told me we didn't drive enogh to charge battery
at the time car only had 14000 mi and sometime parked in driveway for week
may be make sence
couple month later drained again and samething lost sound and NAV
this time I dis-connected battery cable waited @30 min connected back
wow, radio work and nav worked But,
when I inserted CD display said "loading" for 20-30 seconds and shows "Device unavailble"
I'd took to dealer again
they said My battery was bad and need new comand unit
replaced battery but $3000 for comand unit?
it was too much for me
been without CD player since
is anyone may be have idea or tips that I can try?
so far what I tried is disconnet batt, disconnect plug at module under back seat and re-connet hour or so
But no luck
Thanks
JW