does not appear to be a set of instructions, while my German is a bit rusty the only thing it says in insert instructions here.

Likely cause ESD micro electronic surfaces are extremely touchy to ESD and Most likely you will not see any improvement you either just need to live with it or get a new phone ESD safe work are ESD safe tools all are helpful but even I as a pro- still have this issue sometimes

Actually there are cables below the battery that you can and will damage Heat gun and Isopropyal alcohol 99% pure or greater

a Blow dryer does not apply enough heat to remove the glue some 99.7% pure isopropyal alchol will get it free you will need a credit card or something as such and have to work it in to get it to remove I recomened a heat gun they get much hotter and are able to heat the glue up enough to give you some play

you most likely disconnected the small little cable next to the battery cable that is for wifi on accident simple solution open it up then remove the plate that covers the bat connector there are 2 cables that sit staged the one on the bottom of the phone is alinged to the right the one on the top is to the left in the lower left corner below the battery cable there is a small wire sitting right next to the second connector the one aligned to the right you could have bumped it when you popped the bat cable out