Hi. If possible, repost all of these details on badcaps forum -> laptop repair. Myself and others monitor that thread and someone will post ideas to proceed with your repair.
For starters, a hot air tool is a must for such repairs. The tools are not expensive and required to remove / replace SMD parts. Review for example the BEST 863 hot air tool (Quick clone) on Aliexpress. There are many others on the market but we use the BEST tool since the vendor claims they can offer us spare replacement part, if ever required to service our machine. Like the fact that we can dial upto 550C on the temp but also suggest an underside pre-heater for heavy copper plane motherboards - like Asus. We have seen cases where even with full heat + high air pressure, we could not remove the SMD BIOS SOIC-8 device.
Moving on, remove all power. Meter in lowest resistance mode (2k scale is ok). We wish to check if your first 2 mosfets that hit the DCIN are ok or defective.
Measure the resistance between:
source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)
Post the readings. Repeat the test for the 2nd mosfet mated with the charger IC.
Post the readings. We are checking for a low resistance reading that will indicate the mosfet is defective and must be replaced. If you see 'OL' = over limit on your meter, then change the scale to the next higher setting. A high resistance reading is good and may confirm that the mosfet is ok.
If the mosfet readings are indeed high, then proceed to very very very carefully, measure the voltage (DC scale of 30v on your meter) on the TI charger IC and post the readings.
Be careful on these measurements so that you do not short the charger IC pins and cause damage. We are interested in the voltage on each pin of the charger IC such as ACOK, ACDET, etc.
Also, this charger IC will boost the DCIN voltage (19vdc) to +6 to enable the GATE of the first 2 mosfets to allow for the voltage to pass through onto the main logic board rail.
If you DO NOT see the DCIN voltage on the main power rail then remove all power again -> meter in resistance mode -> check the resistance to ground of the 2nd mosfet, pins 5-6-7-8 = DRAIN. We are checking to see if there is a LOW resistance on this rail which often means there is a shorted cap on this rail. With a shorted cap (tantalum is often the bad boy), the charger IC is measuring the current and turning off the mosfets to prevent further damage.
First start with the mosfet resistance values -> then the voltage readings on the mosfet pins.