How to test "Q6" component

[electrofix]

Currently I have a capacitor meter that is only working from microusb port.  It does not turn on using battery port.  Does anyone know how to test "Q6" below?

[Grandchuck]

No one seems to be around to take a stab.  So, here goes:
Is the battery voltage at point 1?  At point 2?
Q4 seems to be the driver for Q6, so it could be the problem.
Apply a few volts through a 3.3 kohm resistor to point 3 and see if point 2 goes high.

[electrofix]

Grandchuck 

Here are the voltage reading results:

Point 1= 2.94V
Point 2= 0.4V
Point 3= 2.94V

Resistor test to follow...

[Grandchuck]

Point 3 is already high.  Try pulling it low with a resistor.

[golden_labels]

Knowing, what Q6 is, would make testing much easier and reliable. The component has markings. Please provide them.

[807]

Giving us the model number of the meter might help too.

[electrofix]

Giving us the model number of the meter might help too.

It is an Excelvan M6013

[electrofix]

More close up pictures with microscope:

[u666sa]

Obviously you have a bad battery. 

To test Q6 you gotta find out what it is, transistor or mosfet, it's done with markings on it. You goggle the markings, and get an idea of what it is. Then you pull out your multimeter and test off circuit.

You can also connect power supply to battery terminals, see if it is the battery or not.

[DavidAlfa]

Leave it connected for few hours.
Normally devices consider 3.7V 0% battery, so at 3V they won't won't turn, ever.
Measure the battery voltage from time to time, this simply seems a case of deep discharge, if the battery voltage doesn't increase even bit you might have a charger circuit problem, but also sometimes the system becomes unable to charge once it reaches such low levels, so you might also try to charge it manually by setting a PSU to 4.2V, limiting the current to 1/3 of the battery capacity, so if the battery is 1Ah charge it at 300mA.
Apparently it's unsafe to provide high currents to deeply discharged batteries, so I always did like this, never had a problem.

[gamalot]

Q6 is a P-channel MOSFET VB2290.

https://datasheet.lcsc.com/lcsc/2211091100_VBsemi-Elec-VB2290_C416211.pdf

[electrofix]

Leave it connected for few hours.
Normally devices consider 3.7V 0% battery, so at 3V they won't won't turn, ever.
Measure the battery voltage from time to time, this simply seems a case of deep discharge, if the battery voltage doesn't increase even bit you might have a charger circuit problem, but also sometimes the system becomes unable to charge once it reaches such low levels, so you might also try to charge it manually by setting a PSU to 4.2V, limiting the current to 1/3 of the battery capacity, so if the battery is 1Ah charge it at 300mA.
Apparently it's unsafe to provide high currents to deeply discharged batteries, so I always did like this, never had a problem.

Hi David, thank you for your reply.  I probably did not explain the issue correctly.  This meter does Not charge the batteries.  It uses normal batteries(Two AA Batteries, See attached picture).  The unit used to work fine from just regular batteries.  (It does not use rechargeable batteries).  All of a sudden it stopped working from batteries and only works from the usb connector.  Even if I put in two brand new AA batteries, it does not work.  As soon as I plug it into USB power, it works, if I remove the USB power, it turns off.  What I am trying to do is to see how I can fix it so it works off of battery power again.  Sorry if I caused confusion on what the actual problem with the unit is.   

[DavidAlfa]

Take the DMM in diode mode and measure this, without any power source connected!

[electrofix]

Hi David, thank you!  I got OL for the test you mentioned.  However if I reverse it as seen in the picture, I get .44.

[DavidAlfa]

Expected if it's a pfet.

Point 1= 2.94V
Point 2= 0.4V
Point 3= 2.94V

And with those readings, it seems it's ok. Now show the rest of the pcb!

[electrofix]

Thank You David attaching new files. 

[electrofix]

More pictures...