phone wont charge after replacing subboard

Question

Samsung Galaxy M51

The Samsung Galaxy M51 is an Android smartphone which was released in August 2020.

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hesab @hesab

İtibar: 13

1

Gönderildi: 5 Tem 2023

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phone wont charge after replacing subboard

short version:

bought phone

dropped phone a few times

phone stopped charging

replaced subboard but had to hit the phone for it to start charging again(it stopped charging daily)

dropped phone in water with detergent

phone stopped charging again

replaced subboard

charging worked for 5 minutes

charging no longer works

what now?

long version:

I bought this phone new, it worked for a while, dropped it a few times, then it didn't charge anymore.

I replaced the subboard, phone still didn't charge, I dropped it by accident. Then it suddenly would charge, a few hours later it stopped charging again. I tried hitting it to simulate a fall (stupid, I know. but....) then it started charging again, I have no clue why.

I kept going like this for a few months (like 4-5) phone doesn't charge? hit it.

last week I dropped it in hot water with detergent. I let it dry, booted it up a day later or so, it still charged at this point but the screen was acting up. I shut it back down again and took it apart the next day to check for any damage. I didn't find anything and disconnected and reconnected the subboard and everything seemed to be fixed but I later realised that the phone wouldnt charge anymore.

I replaced the sub board today, the phone charged for a good 5 minutes and now it won't anymore after rebooting. What do I try now?

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Justin Castle @erelectronics İtibar: 3,2b 19 7 3 · Answer 1 · 2023-07-05T17:53:47-07:00

Most likely water damage and/or corrosion caused by the detergent water damaged the logic board. If you can, take it apart again, fully remove and disconnect the motherboard from everything, using a soft bristled toothbrush and 90%+IPA clean the full surface of the motherboard, both sides, and make sure to get any contacts where things plug in. Also get the other components (NOT camera lenses) and their contacts.

The mystery is why the "hit it to charge" function earlier.

I am unfamiliar with samsung M-line phones, but I have extensive experience with S-line and A-line, along with Notes, and a few from the J-line. Is this more of a flagship specs/pricetag (i.e. the S20 that released the same year) or more budget device (i.e. the A12 that released the same year)? Something I have noticed with the A-line budget phones specifically is that the connectors aren't as sturdy and robust as on the S-line phones, and more than one of my clients have had motherboards with the connectors simply break off, either in whole or in part, from the motherboard. If you have a magnifying glass or microscope, see if you can inspect the connection where the ribbon cable between the sub board and main board plugs in, and if that connection has any bent/broken pins, or cracks in the plastic, or is coming loose and separating between the motherboard and the plastic connector, that is likely where your problem is from. Really the only way to fix that would be to reattach the same or a new connector via yourself or someone who has microsoldering tools. Though that is just a hunch and I have nothing to support that theory.

oldturkey03 @oldturkey03 İtibar: 783,4b 1,1b 893 2,3b · Answer 2 · 2023-07-05T18:27:21-07:00

@hesab I just want to add to the great answer provided by my colleague @erelectronics This "hot water with detergent" needs your attention. the detergent is what will short circuit your phone. You do need to take care of it first.

For now you want to stop continuing to try to charge, sync or otherwise use your phone. This potentially can make a bad situation worse. This may further damage your phone.

The next thing to do, is to clean it. Disassemble your phone using these guides Samsung Galaxy M51. Remove your main board as well as the sub-board . You must remove all EMI shields. If you do not remove those, you might as well not do anything. After you remove those, clean the boards, connectors and all with +90% (better if you use an even higher concentration like 96-99%) isopropyl alcohol. Follow this guide, and even so it was written for an apple iPhone 3G, all the points are still pertinent to your phone. While you clean your board, check for any obvious damage, like burned or missing components etc. When it is properly cleaned, replace the battery. All these steps are to avoid delayed failure caused by corrosion. Best thing to do would be to clean it with an ultrasonic cleaner, but if you do not have access to one, this will at least help. Once all this is done, reassemble your phone and reevaluate. Until it is cleaned, everything will only be a guess. Even with all this, water damage has only a small chance to be fully repaired, but at least you can give it a try.

Since your phone still appears to come on, check the not-charging flowchart from Samsung

To determine where the components are, open this document Component Layout and use the search function of your PDF reader.

BTW one of the issues on this model, is the flex cable coming from the sub-board to the main board. They somehow fail more than usual. I would consider replacing that as well.

Should you find "things" that are just weird looking etc, post an image of that with your Question. That way we can see what you see. Adding images to an existing question

Samsung Galaxy M51

phone wont charge after replacing subboard

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Adding images to an existing question

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