Check the buttons on the radio. One may be "jammed" especially the MON button. It would indicate receive all the time. Check for dirt around the button and case, it can surprise you what little can jam a button. I clean around the buttons with cotton swabs and alcohol. Be careful and do not use sharp objects to move the buttons back and forth, side to side, up and down. I suggest your fingers, or a dull letter opener or screwdriver, but little force. If the MON or other button does not release, you may need to take the case apart.
http://www.motorolasolutions.com/content/dam/msi/docs/business/products/two-way_radios_-_unlicensed/_documents/tlkr-t_series/static_files/t5_manual_eu.pdf