Power Adapter Warning + Backligt Keyboard not working.

so.. hi,

is this thread still featured? i hope so.

i had this strange thing going on with my backlit keayboard on dell e6510.
initial laptop got a normal keyboard, without backlight. i ordered a new one and replaced it.
backlight wouldnt start working on my machine.
i then was at a friends of mine, which had e dell precision, with working BL keyboard.

i first thought, my ordered keyboard was just damaged or sth. like that.
we changed boards, just for verification and. his backlight was working on my machine, and my keyboard was working on his.

i was happy about my new backlight. until..

some days later i received the POWER A/C alert message booting up my dell.
it said "The AC power adapter wattage and type cannot be determined", that my dell could not charge right and that the system setup will be adapting and might cause an decrease of performance.

its charging like  hero. everyday, everyhour. but my keyboard backlight stopped working.

on some days it works for ~0.5 s - 20 sec. after initial startup of the machine. mostly on loginscreen.

any answers are welcome.
maybe someone knows about this strange problem.

p.s.: oh yeah.. by "keyboard not working" i mean the light of it. all keys are fine and doing their job.