S21 Ultra stuck searching for signal, can't connect to mobile data

[Kelsey Thurman]

(searching) and signal bar is crossed out

Ever since my phone restarted it has been stuck searching for signal when on mobile data. I am able to connect to WiFi and use bluetooth but I get nothing related to mobile data. I have tried all the common fixes for this with no luck. I have pretty much narrowed it down to a hardware problem. My question is: what components could possibly cause this. I am aware that there are a few different antennas inside the S21 Ultra but I have not been able to find much detail regarding the function of each. Could a bad 5G antenna be the cause of this or would the symptoms be different if it was? Again, I don't have any mobile data, even when turning off 5G in the settings. If anybody has experience working on the S21 Ultra or know what may be causing this issue your help would be greatly appreciated. Thanks!

[Kelsey Thurman]

I solved the issue. I had to order a new charging board to replace the old one. Some other symptoms that started appearing were my bottom speaker stopped working and my SIM card kept disconnecting or just not reading at all. If you also have these symptoms its likely that you also need to replace yours. I'd suggest taking it into a repair shop or if you are willing to do it yourself its not a bad repair. All you have to do is remove the back of the phone which you can find videos online on how to do that and you can order the charging board from ebay for about $15-20. If you go the self-repair route I would suggest that you also buy a new adhesive strip for the back or you can buy a whole new glass back kit.

[Kelsey Thurman]

oh yeah, I also should say that the new board fixed the speaker problem and the SIM card problem since both the sim reader and speaker attach to the bottom board. Also, I was quoted about $120 for the repair from a local repair shop so expect something around that price.

[Kelsey Thurman]

Hey, sorry I missed your reply. As I stated in another reply, I ended up replacing the bottom charging board which contains the SIM card reader. At least for me, as symptoms developed with more and more issues involving the SIM card, I eventually figured that the board must be the problem. So far it has been working well since I replaced it. 

[Kelsey Thurman · Accepted solution]

I wrote some previous replies but IDK if they went through because I can't see them in the thread. I ended up solving this problem by replacing the bottom charging board in the phone. The SIM reader is connected to the board as well as the bottom speaker which also happened to not be working at the time. Anyway, if you are having the symptoms I described above as well as well as problems with the bottom speaker and SIM card reader it's probably the charging board. I replaced it myself which wasn't too bad to do (you can watch some teardown videos on the S21 Ultra on youtube to see how to get to it). You can also probably get it replaced at a repair shop for relatively cheap (I was quoted about $120). Hope this helps!

[mfbas]

Hi Kelsey,

Thank you so much for your update! I took your advice and replaced the part (bought it on Amazon and followed a random YT video) and my phone is working like nothing happened! Again thank you!

[Kelsey Thurman]

Awesome, I'm glad I could help!

[Michg33]

Thanks for posting this solution! I am having similar issues, and have tried switching to an esim. Did using an esim not fix the problem for you? Just trying to check that I actually have the same issue.

[poppanitrous]

Same issue.

I have metro pcs and the store can't figure it out. My s21 has been fown now for a week

I've tried network node, network reset..nada

Sometimes cycling the phone it will work for maybe 1 or 2 mms.messages and they will be minutes late but it won't send pics via mms..it has to be a hardware.

[poppanitrous]

 going to go back and buy an s20 ultra throw in a 1tb sd card and have 12gigs ram and call it the day

[poppanitrous]

I have done EVERYTHING..local metro pcw has tried mobile network reset..it will not find fast.metropcs.com in the network refresh...

New phone time..period