Sim card not ready

We have a CPE that was uninstalled from client’s location in good working condition as far as we know.
When were testing it at the office, it boots up properly then all the lights start blinking.
Logging in to the CPE, it shows that the Sim card is not ready. We upgraded the firmware to the latest and reset it to factory but that did not fix it. We had to remove the Sim Card and re-install it several times before it started working again. There were no scratches or any damage on the Sim card.
Any idea what could have caused it or has anyone experienced this issue?

I have the same issue with SIM moving from scanning to checking and checking to scanning.

Have you tested other SIM cards as well to reproduce the issue of not detecting SIM card? If so, it could be a faulty SIM card reader in the CPE. You can email support_na@baicells.com summarizing the issue to start the RMA process if needed.