Potential Toshiba Backlight Problem

Hello,
Well I'm currently having an issue with my laptop most likely to do with the backlight. What has happened is I was visiting my father and he decided to borrow my charger for his toshiba laptop. Well is charged sure enough but when I came back to find he had used it the charger wasn't in the best of conditions. Anyway I had to continue using it until a replacement would arrive, meanwhile the USB ports would have a light flow of electricity running through them (lovely and safe eh?)
Anyway now to the screen issue. I turned my laptop on the other day to find that the backlights came on for around 4 seconds then shut off. I let windows load and after playing around with switching the screen on and off (by changing the video card output between an external monitor and the laptop screen) I managed to get the backlights to stay on. Though there was now a slight buzzing noise that got louder the more the brightness was turned down. Also there is a slight flicker in the screen that lessens the more the brightness is turned down.Now most times I turn the screen on the backlight doesn't work unless I flick the screen on and off a few times. Today however it simply refused to turn on at all. I mean I can flick through and make the backlights turn on for a few seconds but they are at full brightness and then simply turn themselves back off again.
So what I really need to know is what the problem most likely is. Is it the backlights or is it something else? Thanks in advance for your time and effort.