1 betty ic

betty ic regulates charging, light and charging voltage and also supply power.
If damage betty- handset can not charge not glow display light charging shows but not chage. And handset can be dead.
We can find betty ic in 5130,2700,6500,5610,n95,6120 etc

2 avilma ic

avilma is uem power ic.generates power to uem
avilma manage- power regulating,mic, buzzer,speaker.
Damage result in handset dead.flashing not complete means flashing done but not in ui setting mode. White screen, insert sim. Mic,speaker problem etc.
We can found avilma 6120,5130,95 etc

3 thavo ic

thavo ic charging regulator ic which can be f0und in 3110 6300 n70 etc damage result in no charge no handset on. And no light.

4 retu ic

retu ic is uem regulator ic which generates sim, mic, buzzer.display. And sound. And also problem in flashing. But if does'nt work one of them first you have to change other filter ic like display ic mic ic ringer ic etc ok.