S7 Edge SIM 1 won't accept another SIM card

[Android Central Question]

I brought my S7 Edge into pool without realizing the back cover was already opened a bit because the battery was a bit leaked already, you know what was going on after that --skip-- Problem : SIM 1 was not working, but SIM 2 was still working --skip--

Suddenly after a week or 2, SIM 1 worked back like a miracle. One day I decided to change my SIM card to get a better network provider, but once I put the new SIM card into SIM 1 slot it was not recognized. Then I tried to put back old SIM card into SIM 1 and new card into SIM 2, they worked fine, both can get 4G (LTE). I tried this a lot of time and need your help to describe what is the problem.

NB : Please don't give answer like throw the phone buy a new one. I knew and planned to buy a new one, but before that at least I still can use my current phone. I need to know why SIM 1 slot wont accept another card even though it is from same provider.

 

[Tim1954]

Try the usual troubleshooting. Try same sim in another device, to work out if it's the sim or the reader...