Will not move

I purchased my Deluxe 4 Dolphin last summer. I have only used it twice this summer and both times it hasn't ran properly. When I select time it only runs for approx 30 min. The bag inside is very clean & still looks brand new. Inside the unit I see no debri and it also looks new & clean. I place the Dolphin in water upside down & submerge under water to release air & then let it sink to the bottom of the pool. I then press the power button on the stand & the first light to appear was the yellow light below what looks like a deck of cards and it goes off leaving nothing lit. I press power button again & all the lights come on & flash and then go off. I press power button & reset button, same thing. I unplugged the power supply and tried everything all over still same thing. Dolphin remains motionless. I pulled him out of the water. I am thinking I will have to take it in to the supply store where I purchased it.

I need help.
Teresa