Having mid-range or higher-end phones like Samsung does not guarantee that the devices will not fall victim to any issues. Samsung Galaxy A02 and A02S have faced issues in the past, and one of the most common problems is the no sim card detected error. Whether the device is not detecting a sim card or throwing errors like No Service or No signal detected, we’ve listed some fixes to eliminate those issues.
In most cases, sim card-related errors like no sim card detected, no service, etc., can be easily fixed. But, sometimes, the problem occurs when the sim card is damaged or there’s some network issue in your area. In any case, applying the fixes we have listed below is worth applying.

Here’s what to do if your Samsung Galaxy A02 and A02S are not detecting SIM card
Fix 1: Turn Airplane Mode on and off
Whenever you face any sim card or network-related issues, you should turn on the Airplane Mode and then turn it off. This method does the trick most of the time. This method disconnects your device from the wireless system until the option is not turned on.
To turn on Airplane Mode, Navigate to Settings > Connections > Airplane Mode and tap on the toggle next to Airplane Mode. Alternatively, you can turn on the feature from Quick Settings.