Samsug Galaxy S4 - Impossible to switch on
ok i know similiar prolems have been posted on here before, but there never seems to be any conclusive answer. I tried to switch on a friends s4 recently, but all t did for me was stay completely black and unusable. when i plug it in, it either stays dark and starts vibratiing when i press buttons, or it just shows the grey battery with the stuck "loading-circle". After countless times of removing the battery, trying to get into download mode, trying to reboot etc i used my galaxy s4 extra battery kit, charged the phones battery to about 17 percent and put it back in there, and voila, i could switch it on without a problem. After 2 minutes of meddling around with it it requested an update, i pressed ok and the phone started rebooting. since then i was not able to get any reaction besides some short vibration bursts from it and the screen stays completely dark. is there any known way to resolve this problem?