Did you ever remove the SmartTILE-Fx CPU board from the carrier board previously?
It sounds like the SmartTILE-Fx board may have suffered some damage.
However, the best way is to request for an RMA (email support@triplc.com) and ship the PLC back to our office for testing. It is likely to be repairable unless there was catastrophic damage to the board.
Please include your company name and contact person name when contacting us. Some explanation of what the PLC underwent would be helpful for diagnosis.