Radio didn't shut down

[MuRCieLaGo]

Hi,

I just worked on my 1991 ZR-1. When I removed the ignition key, the radio backlight didn't shut down. Key on, I could only see the backlight, also.

Backlight was always on no matter what I did. It is an aftermarket radio and I never had any issue with it for the past 2,000 miles (since I bought the car).

I disconnected the battery for 5 seconds and connected it back and now... Everything works fine, just as it should.

Why it didn't shut down? I didn't like that... Could it be because I used a 400 amp jump starter to start the car (battery was drained, left the hood open for too long)? Was it a bad idea to use a 400amp jump starter? The positive cable of the jump starter was hot when I removed it, and it didn't even achieve to start the car. Had to boost it with another car.

Thanks!