Well, unfortunately if you have flashed the bios with an incorrect version then your options are rather limited and you are going to have to part with some money.
There are companies who can (sometimes) repair/replace the bios chip
http://www.motherboard-biosflash.co.uk/ being an example of one but you need to make enquiries to help you decide if it is worth doing or if you should buy a new laptop.
I suspect that the original problem with the backlight is due to a faulty FL inverter board and as such would not be helped by flashing the bios anyway.
Learning all the time.