I've got a friend's ASUS M5200 laptop that I've offered to look at.

It works fine when connected to it's power supply but dies instantly if the
power is removed. There are only ever two lights on on the front of the
laptop, one for the mains supply and one for the hard drive. The battery
light never comes on. The power meter in Windows does identify the battery
and shows it as having zero charge.

I've tried battery recalibration and a new battery has also been tried but
neither helps, it still refuses to charge. More in hope than in expectation
I've opened it up to have a look around but there's nothing obvious to see.

I'm guessing something has gone wrong with the internal charging circuitry.

Is there anything else I can do or have I come to the end of repair options
(short of motherboard replacement)?

Tim