Had 3 AV2000s working fine, then added 4th unit for laptop internet in another room.  Worked great for 2 or 3 weeks, then stopped.  When I try to pair with base unit, it fails with blinking red/green light.  I have tried it in multiple rooms, including same room as base.  Have tried resetting this unit (hold for 15 seconds).  Did this unit go bad?  Thanks in advance for help!