Same problem like many others, in this case with A70. I've changed adapter + cable (original), and the charging board where are type C port - 0 result. The only temporary solution was factory reset. After update, the problem comes again. When i lock the screen, charging starts and stops repeatedly. If i unlock the phone and leave it , the problem gone. From Samsung try to convince me, that the problem comes from the battery, but that's not true. Before couple updates , there was no problem. And the factory reset proof that.
I would have suggested to take the phone to a Samsung Experience Store or Samsung Service Centre, but I see you mentioned in your post " I've changed adapter + cable (original), and the charging board where are type C port - 0 result. "
If you've effected a Repair yourself then unfortunately your warranty will be voided and Samsung may not now be able to offer support.
I wish you all the best. Take care. 😎
Daily Driver > Samsung Galaxy s²³ Ultra 512Gb in Phantom Black.
The advice I offer is my own and does not represent Samsung’s position.
I'm here to help. " This is the way. "
The warranty expired long time ago. Nothing damaged when i replaced the charging board. The problem appears only when i lock the phone. If i do some stuff on the device while charging, there's no issues. Another situation - if i use smart view , the phone screen turns off and still charging without any problem.