Chances are its from apples terrible design of having ALL the hot air from the cpu and gpu blowing on the hinge glue. Not your fault. Put some new epoxy and it should be fine
If you remove the back glass again will it power on? It is plausible that your adhesive may have got onto the motherboard and is shorting something? although not many adhesives are conductive.
You will need to replace the entire LCD assembly. You have cracker the main LCD under the glass. https://www.amazon.ca/Eaglestar-Digitizer-Assembly-Faceplate-5-Silver/dp/B0755D8BW3/ref=sr_1_6?ie=UTF8&...-6&keywords=lg+aristo+lcd
Where can you get a battery?