I am experiencing this exact same issue. I have a 1992 ES300 with an aftermarket Alpine/JL sound-system. Everything worked just fine for about a year, and then the battery was disconnected and the car sat in the garage for about another year. When a new battery was installed and connected, everything works just fine...but the stereo system does not power on. Fuses, et al, are good. I'm hoping someone can shed some insight on this problem.
Also, not sure if it's related, but the 'Air Bag' light on the dash is now lit. This is something else that wasn't happening before the battery disconnect.
Thanks in advance to anyone who can help.
