Precious Metal

Hi all, My mother in law's 2007 LS460 is having a Nav meltdown. It doesn't get driven much so the battery died. I trickle charged it and everything seems to be fine now except for the nav. It says "data not readable, take to dealer" Car has 60k and is out of warranty so I don't want to go to the dealer and beg for help. her new LS460 is arriving next week and I don't want to try to sell this one with the nav not working. Any help is appreciated. Thanks