TX 5.0 RC treadmill?

when you punch in the auto speed it starts up as if its running along with the timer, by the walking pad does not move at all and then after about 8 seconds it beeps and shuts down. everything looks like its hooked nothing loose - checked the fuse - its working, cannot find anything thing wrong - unplugged it thinking maybe something would reset - but nothing does the same thing - starts up -pad does not move and then shuts down. what can it be.