Toshiba 20AF41 Won't Start- only clicks every 5 seconds

I bought 6 Toshiba televisions 5 years ago (model 20AF41) for use in my dental office.   They are (were) used for patient education and for video playback from my intraoral cameras.  It was fantastic.  3 out of the 6 televisions are now in my basement with the exact same problem.  They won't turn on.  Instead they just click every 5 seconds and the power LED light remains on.  What's up with this?