***Just got my 2010 model working.***
***''The batteries were no longer making proper contact with the motherboard.''***
There had been minor battery corrosion on the spring contacts in the battery compartment from the AAA batteries that were left inside. After cleaning that away with a wire brush and some alcohol the device still wouldnt power on.
***I opened the device by removing:***
# ***The keyboard, by pressing the back switch and sliding off***
# ***2 philips screws (+) to remove the optional rechargable battery compartment from the upper back***
# ***6 torque screws(*), two of which are inside the rechargable battery compartment and prying off the back, which takes some effort but its quite sturdy***
# ***6 small philips screws (+) on the motherboard and lifting. If it doesnt lift easily, pressing and lifting the display from its front face helps. Be mindful of the delicate ribbon which connects the motherboard to the display board.***
I examined the motherboard and found a vibrant blue precipitate from presumably the gold traces around the motherboard and the battery corrosion. This cleaned away quite readily with a clean cotton swab dipped in isopropyl alcohol and a can of compressed air.
On the underside of the motherboard were four gold rectangular contact pads where the AAA battery's four small steel arm-like contacts would deliver power. ***These pads had been burned away at the point of contact***.
I placed flux on the pads, and using a soldering iron and some solder, left a bead at each of the burned contact pads. I ensured that the pads were not too tall so as to remount the motherboard. This essentially bridged the holes on the pads. Putting it all back together and pressing the power button yielded a success!
***''Please practice safety when using solder and soldering irons, including proper ventillation!''***