2000 LHS Battery Replacement Problems w/ CD Changer

Hi,
I just had a local shop replace the battery in my 2000 LHS today. They
tried to keep power to the car while they were doing it but had to
disconnect it for a few minutes to put a new end on the negative cable.
My problem is that the CD changer quit working in the process. All of
the lights on the changer flash in unison and that is all it will do.
Won't play, won't eject the CDs that are in there, won't do anything
but display ERR on the radio display. The radio and tape player work
fine. Is there some sort of reset procedure that needs to be done?

Thanks,
Nevin