Why is my iPhone 7 having cellular issue problem. It can’t detect my sim and most time writes “No Service”

See if this applies: iPhone 7 Repair Program for "No Service" Issues - Apple Support

_Temitee wrote: "No, it doesn’t have its original battery

currently 99% but it’s been like that for a while now"

Was the battery replaced by a qualified technician using a genuine iPhone battery?...

About genuine iPhone batteries

Repair Provider Verification - Official Apple Support

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Temitee ~ Does your iPhone 7 still have its original battery?

And what's the Maximum Capacity % here?...

Settings > Battery > Battery Health

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