I was given a eleaf istick 20 watt model that would not turn on....You Tube is My go to for info on tearing into things so i replaced the on board battery with a Efest 18650 2500 mAh flat top...I had charged it first and hard wired it in and put it back together and it worked!....lasted two days of vaping with a few different attys,C4 clearomizers,a Nimbus RDA with two coils at 1.9 Ohms,and a small single coil bully clone...When it shown the lock on the screen I put it on a 1 A. charger and it would not take a charge...So it was opened again and I carefully put it on My charger and it took a full charge,back together and it lasted about the same time....I'd like to make the charging port work or make the battery removable/replaceable I also have the flip hinge thing on it too because of all the thread complaints...Any and all info will be great,thanks....Vapercatz....