How should I check this PCB circuit board

[daisizhou]

Hello everyone.
I am debugging this PCB circuit board.It has been running steadily for over a week,But now it can't load the program.
Because when I checked the LED indicator light, only the power indicator light and TX indicator light remained on, while the RX indicator light did not flash
There are 2 types of memory on the motherboard, namely AT45DB021D (SOP-8), MT29F2G08ABAEAWP (TSOP48), and SDRAM-W94AD6KBHX6E (BGA)
DM9161AEP is an RJ45 network communication conversion chip used to connect network switches

AT91SAM9G45-CU-->https://www.alldatasheet.com/datasheet-pdf/pdf/313136/ATMEL/AT91SAM9G45.html

I originally planned to use an oscilloscope to check the "RESET" signal,But the SDRAM chip does not have a "RESET" signal.
I soldered the BGA chip again, but it's still the same.
I don't know where the malfunction occurred, how should I check it,If you know, please let me know. Thank you

[retiredfeline]

Sorry, I don't have any answers for you but the CB already stands for Circuit Board, so your question becomes How should I check this Printed Circuit Board circuit board. 

[daisizhou]

thank you.I am looking for a way to test it, and I suspect it may be because the program did not load

[daisizhou]

I have read the internal firmware of AT45DB021D (SOP-8)

I don't know if there is firmware storage inside the microcontroller AT91SAM9G45-CU,If there is no firmware inside AT91SAM9G45-CU, I will purchase a new AT91SAM9G45-CU to try replacing it,This is my current preliminary plan.
If you have any better suggestions, please let me know. Thank you

[MathWizard]

Have you checked all the chip Vcc voltages ? I would try and rule out as much normal analog problems 1st, before buying anything. What is the PCB for ?

[daisizhou]

The motherboard has a 5V voltage input, and I have measured the VCC and GND of most chips, which are normal。
The motherboard is a type of RS232 or RS485 signal to RJ45 signal, which looks like a router,，Normally, the IP address and port number are stored internally，The host sends data to the internet through it

[daisizhou]

Do you have any better suggestions?
It looks like AT91SAM9G45-CU, there is a bootloader inside this microcontroller, it is ARM9 series, so I am looking for a cheap programmer to try to read its internal program.
If you have better suggestions please let me know, thanks

[fzabkar]

I can see several inductors, especially on the daughter PCB. These are normally associated with switchmode power supplies. It would measure the voltages at the inductors.

[daisizhou]

There is no voltage on this sub PCB board，Looks related to the white interface,There is an AC to DC bridge stack on the sub PCB board

[daisizhou]

Who can tell me if AT91SAM9G45-CU can store programs internally?
What I mean is that I will try to replace AT91SAM9G45-CU.
If AT91SAM9G45-CU memory has the function of storing programs, then I will be doomed to failure

[fzabkar]

Who can tell me if AT91SAM9G45-CU can store programs internally?

The datasheet states that the IC has 64KB of internal SRAM and 64KB of internal ROM (SAM-BA monitor).

http://ww1.microchip.com/downloads/en/devicedoc/Atmel-6438-32-bit-ARM926-Embedded-Microprocessor-SAM9G45_Datasheet.pdf

The chip needs several supplies, including ...

VDDCORE, VDDPLLUTMI, VDDPLLA, VDDUTMIC = 1.0V
VDDIOM0, VDDOSC = 1.8V
VDDIOM1, VDDIOP0, VDDIOP1, VDDIOP2 = 1.8V or 3.3V
VDDUTMII, VDDANA = 3.3V

[daisizhou]

Thank you, it seems that there are only 64KB SRAM and 64KB ROM inside it。
I tried to replace it completely,I will give it a try, hoping to succeed

[daisizhou]

I replaced AT91SAM9G45-CU and found that the operating current of the entire circuit board was about 80ma lower than before,It's about 120ma now, it used to be about 200ma.
The motherboard still cannot function properly