Lenovo g580H MB LA-7988P will not start

Hello

I have Lenovo g580 and will not start. I open and made some measurements but I can locate were is the problem could you help me. I measure
PQ301 n1,2,3 19.95 n4 19,95 n5,6,7,8 20.5
PQ302 n1,2,3 19.94V n4 19.94 n5,6,7,8 0V
Pl301 have 0V
Power conector jpwrb1 0v on all pins
Do you think is bq727 (PU301)or some other power IC
Thanks

Hi. Will not start why? water? fall? ac-dc adapter malfunktion?

Measure the voltages on pins 5, 6, 8, 9, 16, 17, 20 of PU301.

I measure the voltages on pins of PU301 and here a results
5- 5.95
6- 2.9
8- 0v
9- 0v
16- 5.96
17- 5.82
20- 19.95

Check PR314 = 390K, PR317= 64.9K

6- 2.9

Correct value 2.7V.

5- 5.95

Correct value 0V
If the value of the resistance is correct replace PU301.

I checked resistors and they are good and then changed Pu301 and problem remained the same. I still have 5.95 on pin 5 on PU301, any other idea

The heaters have the correct value?
Desoldering PQ316.
Measures to power on PL401, PL402.

I desolated pq316 and put adapter and transistor Pq302 immediately heated what shout i do.

Measure the resistance to ground on pins 5-6-7-8 of PQ302.
If low do this test:
post5699.html#p5699

Problem solved. I found what was casing the problem it was sort circuit on ceramic capacitor above PL301. When you told me to look for little resistance I thought now I need to look for a sort circuit on MB and imagine the first capacitor that I measure was in sort circuit i changed from a similar MB and now MB is working fine and got picture on my screen.

Thanks

Head around before closing.