it could be the dock connector or another guess would be that maybe the battery shifted slightly and the contact points arent making contact anymore? or maybe the dock connector cake loose off the logic board?
hello tommy, To answer your question yes you do need the sticky strips because it is actually the only thing holding the ipad 2 together unlike its older brother the ipad 1 which has a combo of sticky stips and metal clips holding it together the ipad 2 is literally glued together. which also makes it a pain in the ^@# to take apart becaue you have to use lots of heat to get the glue to release. i hope this answered your question.