My Company was throwing out 2 older model BlackBerry Bold 9700s and I noticed one looked new. After further inspection, it was brand new, but was marked defective. After getting the long dead battery charged and the device wiped of all previous memory, I figured out that the camera was not working (wouldn't start in BlackBerry terms). I researched the faulty camera functionality on Google and found out that it was a widespread problem with this model. I then put my thinking cap on and booted the well-used (read: abused) 9700 and found out that its camera was functioning fine. Unfortunately, the camera on this 2nd device was about the only thing function well so I decided to put on my Dr. Frankenstein surgical gloves and transplant one functioning eye from a willing donor to my blind supermodel.
Thanks to my handy iFixit Essential Electronics Toolkit, their informative BlackBerry Bold 9700 teardown article, and a few YouTube do-it-yourselfers, I was able to save an innocent BlackBerry from early retirement.
Ask not what your old phone can do for you; ask what it can do for another one of your old phones.