Blackview A60 SIM Card detected, but not connected to the service

I am currently using my phone for like 2 months now. My SIM Card is "Lebara". Yes, it's a German SIM Card. Now to the question.

I am having trouble connecting to any service. I literally tried everything. Reinstalling the device, resetting to factory settings, like literally everything I did.

I only flashed TWRP, Magisk and ARCore from Magisk. Since then the Device couldn't boot. I reflashed my device again losing TWRP, Magisk with ARCore. Then just like when my device starts up like normal, SIM Card detected. After setting up the device, and installing System Updates, more things got nasty. Like literally, my phone has lost the service from my SIM Card. Nothing works. Not even API. Nothing.

I will wait for your answers how to fix this. I hope it's not any hardware issue.