Solved! After replacing half of the phone (screen, sub-board, battery), still having problems. Phone shows 0% and restarts every 30 seconds. Is there any hope

[Rendvend]

So, around 2 weeks ago, I dropped my phone (Samsung Galaxy A70) into a puddle. I reached for it instantly, and the screen flashed off. I took the phone, dried it, and I shook any water out of it (there wasn't a lot). I didn't expect the screen to magically start turning on, but it was worth a shot. The end result of the phone at this state: would turn on (the only way i knew is that my watch would connect to it and not disconnect), screen didn't work. After some investigation, there was only one water indicator that was flagged, and that was the one next to the sub-board and the screen. Undoing the connectors, they were both slightly corroded on either side of the connector. The board wasn't corroded, and the main-board water indicator did not get wet, and there were no signs of water damage on the main board. In fact, the only visible damage/symptoms were that the screen wasn't working and the connectors were slightly corroded. I then ordered a new sub-board (the board that connects to the screen and has the charging port/aux) and a new screen. I also ordered a new battery, just to replace the one I had while I was in there, also to avoid having to pry up my old battery and risk it swelling later on. Then, today, I get the final part, complete the job flawlessly. Plugged the phone in, but it wouldn't show a charging indicator. I press the power button, and it turns on! But... once it boots, it says 0% (no charging indicator). After unlocking the phone and messing with it for a bit, it would also turn off and back on after a while of looking through it (under a minute). (It stays on for 30 seconds, and then restarts...) I tried using the new screen with the old board and vise versa, and neither would show a picture. I tried using the old battery, and same 0% (no charging indicator) and not staying on/charging symptoms.Please help. Is this a sign of the main board going out? I mean, I can load up everything and access some files, for a whole of 30 seconds... i just wanted to use my old phone with important files and pictures... i appreciate any assistance, thank you. And yes, safe mode does not work.

 

[Xbox and Windows Gamer]

So, around 2 weeks ago, I dropped my phone (Samsung Galaxy A70) into a puddle. I reached for it instantly, and the screen flashed off. I took the phone, dried it, and I shook any water out of it (there wasn't a lot). I didn't expect the screen to magically start turning on, but it was worth a shot. The end result of the phone at this state: would turn on (the only way i knew is that my watch would connect to it and not disconnect), screen didn't work. After some investigation, there was only one water indicator that was flagged, and that was the one next to the sub-board and the screen. Undoing the connectors, they were both slightly corroded on either side of the connector. The board wasn't corroded, and the main-board water indicator did not get wet, and there were no signs of water damage on the main board. In fact, the only visible damage/symptoms were that the screen wasn't working and the connectors were slightly corroded. I then ordered a new sub-board (the board that connects to the screen and has the charging port/aux) and a new screen. I also ordered a new battery, just to replace the one I had while I was in there, also to avoid having to pry up my old battery and risk it swelling later on. Then, today, I get the final part, complete the job flawlessly. Plugged the phone in, but it wouldn't show a charging indicator. I press the power button, and it turns on! But... once it boots, it says 0% (no charging indicator). After unlocking the phone and messing with it for a bit, it would also turn off and back on after a while of looking through it (under a minute). (It stays on for 30 seconds, and then restarts...) I tried using the new screen with the old board and vise versa, and neither would show a picture. I tried using the old battery, and same 0% (no charging indicator) and not staying on/charging symptoms.Please help. Is this a sign of the main board going out? I mean, I can load up everything and access some files, for a whole of 30 seconds... i just wanted to use my old phone with important files and pictures... i appreciate any assistance, thank you. And yes, safe mode does not work.

Safe mode doesnt work, thats it probably. If possible try backing up all data to cloud or an external device and factory reset if you know how to fastboot. If that doesnt work, check if your warranty takes devices with these issues and hope you get a replacement
edit: any bends? its a budget phone so it probs has bad materials, and a bend could also be one of the roots to the issue.