Hey my cousin has a galaxy sIII mini and at first it had issues with reading the sim card. It would be able to read the sim card then just stops working after about 5 minutes. The phone was then left in her glove box for a day and started working fine. Till recently, the sim card started having issues in that phone again. The simcard works fine in any other phone with no issues. And now there are battery issues. The battery will be full then randomly it would say battery low and shut off. Usually taking the battery out and putting it back in fixed it till it randomly dies again. It's a very annoying issue any advice or information needed I'd gladly accept and provide! Thank you!