IPhone 4 charging indicator comes on but won't charge. What is happening?

I disassembled my iPhone 4 to change my home button flex cable and now I can't charge my phone with my charger or my computer. However my phone is recognized by iTunes. What is wrong with my phone?

You may have to replace the battery.

Haha this happens with my phone sometimes too and i'm using galaxy s3. You need to plug/unplug the charging cable from your iphone and restart the iphone while the cable is plugged or put your device into DFU mode while plugged and and turn it back on and leave it for like 15-45 mins and you will notice a difference in the battery life increasment