We've had similar problems here... DS went from loving his tooth brush to hating it. DH tried him with the electric one a couple of times and he loved it, so we bought him one of the ones for kids with the extra soft bristles. It did say on the package not for kids under 3, but I asked the dentist and he said it was fine. He also said to not use toothpaste until they are able to spit it out, it's really not necessary and if they aren't rinsing and spitting apparently it can cause mouth ulcers and other problems...

Anyway, I would give an electric one a go and just let your LO play with it. DS loves his and wants to have a go everytime we go into the bathroom now.