You need to fix the boot manager problem first by connecting an external monitor to the laptop so you can see and do a system repair.
As for the backlight problem :-
You could have a faulty CCFL lamp or inverter, To determine if you have a LCD screen, inverter or video card problem, read this and follow these instructions.
Defective CCFL backlight, it may have the following symptom: Screen flashs on red/pink and off. Picture stays on in red and slowly be come normal. Picture flickering with dim display or appear black. Picture flickering on and off. All these symptoms indicate that the LCD backlight lamp (CCFL Lamp) has reached the end of the life and all you need to do is replacing the CCFL lamp. Connect an external monitor to your laptop and power the monitor up first then the laptop
, if you see the normal Windows images then the video card and laptop is OK and the problem is definitely the backlight. Dim image and/or dark display on the laptop's LCD screen indicates a faulty LCD backlight and it could be the inverter that supplies high voltage to the CCFL lamp or it is the CCLF lamp is nearly burnt out or burnt out, most likely this is the case.
The inverter can be replaced easily but the CCLF lamp is more time consuming and requires soldering skills.
Check out www.lcdparts.net
for parts, repair service and DIY info