Navigation Problem. Worked Fine & Tried To Update & Now It Doe

[Geno19]

I have a 2001 Lexus LS430. I purchased the most recent Nav DVD from the dealer (previously using original 2000 DVD) and tried to install it. It tried loading and got almost all the way through the process then said disk read error. I took the disk out and noticed it had many scratches on it. The scratches came from the manufacture so Lexus gave me a new one that wasn't scratched. I tried to install the new one and it just said "no disk detected". Tried to put the old one in and it said the same thing. I tried disconnecting the negative on the car battery over night and still had the same error. The dealer took a reader out of another car and put it in mine and it worked fine. They said the problem is definitely with the reader. The Nav worked fine until I tried updating it with the damaged disk that I got from the dealer. They said it is just coincidence that it stopped working at that time. My question is: Is it more likely that reader just went bad at that time (because of the bad disc or not) or that it just partially down loaded the bad disk and needs to be reset somehow? I was reading something on here about a battery in the reader itself and resetting the reader. Does anyone no anything about that or have any other input or suggestions? Thanks!