From experience, info on the 2400 is tantalising but, sadly, dying out. My own machine arrived totally intact (complete with original box, all cables etc. - totally pristine if truth be told)...but dying. The infamous 'green light of death' was the problem and although the online advice about resetting the PMU (i.e. disconnect from AC supply, leave for several hours, hold the reset switch for 30 seconds) did work sometimes but it didn't take long for even that to stop doing the trick. Removing the PRAM battery altogether didn't help so my machine is now little more than a very expensive doorstop.

If you ever find solution to these kinds of problems then it'd certainly be appreciated