I'm sorry to hear that you're experiencing this issue with your Samsung A20S being stuck in Safe Mode. Here are a few steps you can try to troubleshoot and hopefully resolve the problem:
1. Restart in Safe Mode: Sometimes, the phone may get stuck in Safe Mode due to a glitch. Try restarting the phone while it's in Safe Mode. To do this, press and hold the power button until the power off menu appears. Then press and hold the "Restart" option until a prompt appears asking if you want to restart in Safe Mode. Select "OK" and let the phone restart. Once it boots up, try restarting it again to see if it exits Safe Mode.
2. Check Volume Down Button: Since you mentioned that the Volume Down button is not working, this could be the reason why you're having trouble exiting Safe Mode. Check if the Volume Down button is physically stuck or if there is any debris blocking it. You can try cleaning around the button gently with a soft, dry cloth.
3. Force Restart: If the Volume Down button is not working, try performing a force restart. To force restart your Samsung A20S, press and hold the Power button and Volume Down button simultaneously for about 10-15 seconds until the device restarts. This might help in getting the phone out of Safe Mode.
4. Factory Reset: If none of the above steps work, you may need to consider performing a factory reset on your phone. Please note that this will erase all data on your device, so make sure to back up any important information before proceeding. To perform a factory reset, go to Settings > General Management > Reset > Factory data reset. Follow the on-screen instructions to reset your device.
If you're still facing issues after trying these steps, it might be a good idea to reach out to Samsung's customer support or visit a service center for further assistance.