Canon PowerShot SD1400 IS not powering on

[Pleco]

I recently repaired a displaced lens bearing in my Canon PowerShot SD1400 IS and now it no longer powers on. This repair required me to tear the entire camera down to get into the lens assembly. I've spent a lot of time trying to work out what went wrong, but haven't been able to find the issue.

Here are some things I've checked so far:
-The battery is still good.
-There doesn't appear to be any damage to the ribbon cables.
-I've cleaned all the contacts in case some debris was preventing the power button from working.
-I've unplugged and replugged every cable multiple times.
-The camera would display an error message if this was a component issue, so I suspect this is a power issue.
-A visual inspection of the board shows no damage
-Probing part of the power circuit with my multimeter and found no issues with continuity.

Any advice for could diagnose this would be very welcome. I'm hoping I didn't accidentally short something out while I was in there.

[Psi]

Are you sure you put all the cables/plugs back into the correct connector.

Check all flex cables to see which side has exposed copper and check the flex socket you have it inserted into has contacts that match up to that side.
Both flex cables and flex sockets can be single or double sided. So it's easy to get that wrong and have connector pads touching the insulated side of a flex cable.
It can also happen if the flex cable is a mirror image and can be reassembled rotated 180deg.  Sometimes that is fine, other times that will result in the connectors metal contacts touching the side of the flex that does not have any exposed copper.

Check flex sockets for any SMT pins that have become detracted from PCB.

Check ribbon cables for cracks again, they can be hard to see. Especially on the power ones and the ones from the on/off button.

Does the camera have a factory reset feature by holding a button down, could try that.

[Pleco]

Most of the connectors can only be inserted one way. For those that can be flipped, I've ensured the cables have been laid flat and have no twists.

The connector at the top left of the attached image is for the power button. It's in an awkward spot, so I can't see the whole thing, but I've checked it a few more times and can see no damage.

According to the manual, the camera can only be reset via the settings. Holding the power button doesn't do anything.

One thing I forgot to mention is that the camera can also be powered on by pressing the image review button, which uses a separate cable from the power button. This no longer works either.

[Psi]

Time to check voltages.

Do the wires to the power button have any voltage that would indicate its actually looking for a button press.

Voltage on caps around the main processor/mcu.

Also give it a very close look over, ideally with a microscope, but with a magnification lens at the very least.
Look for any parts that might have been knocked off the PCB accidently.

That connector that is missing from the PCB at the bottom is probably some sort of production/debug port.
There maybe a UART in it spitting out debug text, and you could also check voltages their too.

[jzx]

Many cameras have a switch in the card door to avoid hot inserting or removing the card, it is actuated by a tab in the door, if it is not well aligned can impede powering.

[Pleco]

The power button is too awkward for me to trace, but there are pins on the connector with voltages and I believe they're connected to the power button.

There is voltage on the components around the main processor.

I took a high res photo of the board with my phone to get a closer look. All the components appear to be there.

There is one debug trace that is outputting a voltage, may be a data signal. I'm not familiar with these types of ports, so I'm afraid I don't know how to read any message it's putting out.

[Pleco]

It's an old camera, so I suppose it could be worn out, but it was working before the lens repair. I could hard wire it on if you think that might help.

[AndrewEp17]

I'm not sure if its the case on this camera, but sometimes the screws holding the PCBs in place are used to connect the grounds to the chassis. So if screws aren't tight it could cause grounding issues. I've seen that in other equipment i was repairing such as a stereo that would go into protection mode because the some screws holding the main board weren't tight. I'm not sure if your camera works like that but it's something you could check

[jzx]

,

There is one debug trace that is outputting a voltage, may be a data signal. I'm not familiar with these types of ports, so I'm afraid I don't know how to read any message it's putting out.

If you have an oscilloscope, put it on the connector that can be for diagnosis and check if you can see activity. If it is an uart you will see a caracteristic signal and then you can use an usb-to-uart adapter to see what "says" the camera. You have to connect the scope before to power the camera and better i you use the single shot trigger.

[Pleco]

I did a continuity test on the main board and it is indeed grounded to the chassis. The screen, controls, and USB port are also properly grounded. I found a couple components on the lens assembly that aren't connected to ground, but it still didn't power on when I bridged them to ground, so it's possible that's by design.

[Pleco]

I don't have an oscilloscope, but I can try finding which pins have voltage with my multimeter. Looking at the USB to UART adapters available, my camera has more debug pads than are needed for UART. That might make mapping things out difficult.

[jzx]

You can use also a cheap logic analizer, but you must know the voltage of the signals. Probably 3.3V, but what you measure with the dmm is the mean value. Normally the uart has 4 pins, gnd, vcc, tx and rx, perhaps the round contacts, You only need the gnd, that you can take of many places, of the ground plane, and the tx.
The logic analizer software can decode the messages if they are shorts, and discover the baudrate, then a uart to usb and a terminal program is better.

[Psi]

Are you sure you know where all the switches/buttons are and that they are all working.
Sometimes there can be tiny, like 3x3mm, SMT switches with an even smaller leaver poking out of the top or side.
Sometimes the leavers snap off during disassembly, or the leaver get pushed too far inside the switch and doesn't spring back out.

[Pleco]

I've checked the motherboard thoroughly and I don't see any switches beyond the one that shuts the camera off when you open the battery door. I accidentally damaged it while testing it by hand (it must have gotten very brittle over the years because I barely touched it). I've since hard wired it to always be on.

Here are some closeups of the motherboard:

[Pleco]

Wait, I just remembered: when I took the camera apart for the lens repair, I used a metal pair of tweezers to remove the display ribbon cable, which is directly above the pads for the battery contacts (marked in red). I forgot to take the battery out of the camera, so I'm wondering if I may have shorted out some components that are used to detect the battery's presence. Is it possible the camera can't see that there's a battery inserted?

[Pleco]

Looking into this further, it seems like the third terminal on the battery is used to measure its temperature when charging and discharging. I suspect the camera is refusing to power on because it can't read the battery temperature. I'm not sure if the battery is damaged since it still charges fine, but I'm gonna try some other lithium batteries I have lying around. Is there a way I can test it for damage with my multimeter?

[Pleco]

Hooked up a cellphone battery and still nothing. I'm feeling pretty stumped.

[Psi]

Did you try connecting it to the PC to see if it enumerates of USB?
Its possible that may work even without the battery being detected.

[Pleco]

It isn't being detected at all. I even installed Canon's software to see if that would help.