Dead phones

Question

My Nokia model 1100 and 2100 mobile phones recently stopped working. The LCD display briefly showed the state-of-charge bars on the 2100 when I connected the charger but no longer shows anything. The other phone also does not show anything on the LCD panel. Both 3.7V batteries are fully charged (4.15V when installed). I have dismantled both phones and cleaned all the spring contacts using isopropyl alcohol but the LCD panels still do not work.