The first thing I check when having speaker or earpiece issues is to see if there’s any sand or lint or other small particles where the earpiece or speaker is, if that’s the case use a air can to carefully blow out or toothpick or pin
must replace the flex as shown in this picture.... http://d3nevzfk7ii3be.cloudfront.net/igi... Update: i usually buy all my parts from this company...they are in the US and have good quality parts https://www.gounlock.com
looks like when you were removing the glass and being that the digitizer is super sensative....might have scratched or cut a part of the digi....if so...a full lcd/digi replacement is necessary.
it seems like the flex cable for the lcd is not plugged into the logic board all the way....try unplugging the cables....cleaning the ports with alcohol...and re connecting the cables to see if that is the issue
http://www.ebay.com/itm/Home-Button-Flex-Cable-Connector-Replacement-Part-for-iPad-4-4th-Gen-Ribbon-New-/111242419128?pt=Other_Tablet_eReader_Ac... this is a good replacement part...would recomend ordering
there is a app called ifileexpress and you can transfer everything onto there, after google the name of the app and there is instructions on how to put them on your computer.