Flickering screen and battery quickly drain

Dear ifixit,

this is what happened. I had one of those mobile battery that you just plug to the power slot of Iphone and it will charge your Iphone right away.

However silly me ;(, I charge this battery for the first time like this:

wall charger connected to (Iphone with this mobile battery plugged).

It initially won't charge at all.

Now some strange issues I had are:

1. My phone will charge just fine and the brightness is just fine IF it is connected and charged to my laptop. Otherwise, the screen will completely dim and it's almost unviewable

2. It will just charge for a while with the wall charger BUT black out after I left it for a while

any solution to this problem?

Is my screen fried ?

is my battery fried?

or what?

thanks before