Hey there. I have a 4S which I got from eBay. Ok, first off, I would like to mention that I am a qualified electronic service engineer, so I know what I am doing with electronics and assembley/repair procedures etc, BUT... I am looking to find the symptoms of common issues BEFORE I chase my tail and lose my patience (which is not easy to do for me). #1 Bought used 4S from eBay - battery cycle count 960+, and dying within a few hours, from 100% (purportedly, and sometimes and instantaneous drop from ~20% ish to immediate shutdown) #2 Bought a GENUINE battery from a local company (http://appleipodparts.com) - I know these people, they are 4 miles from me, and they are mutual friends of an industry contact, also 4 miles from me, and the battery came with ONE charge cycle logged (they test all their batteries by cycling once). #3 Tested the new battery in the following manner - it came @ 16% charge, and I only had time to charge it to 65%, and then had to go out. It dropped to 10% in LESS THAN AN HOUR AND A HALF, and then shutdown at 2%. Whilst the battery was charging, the back of the phone was warm (not hot, WARM) as is usual. During usage, the back was slighltly less warm then when it was charging, but was noticeably warm, nonetheless. I understand that the ion bonds need to form (?) and that the battery charge retention will increase the more I charge it, but this rapid a drop from 65% to nothing, in SUCH a short time, seems pathetic. I have examined this 4S internally, meticulously, with a magnifying loupe, there is NO internal OR external water damage (dock sensor is tripped red, but that is very common) - headphone sensor is still WHITE, as are the internal sensors. Is there anything obvious I am missing? 3G data and location services were both ON during my initial test. This thing is starting to annoy me now, it's through common sense and clear thinking that it hasn't yet met a high speed hammer... Many thanks, if you are able to point me to CLEAR, KNOWN symptoms (and you are of engineering ilk, and not just some random bod breezing by throwing guesses at me) it would be very much appreciated. Remember, before trying to help, PLEASE DO NOT GUESS when offering advice - I can guess things myself, as an engineer, I am asking for service advice from experienced iPhone service people, thank you Thanks everyone have a great weekend.