If it doesn't have mould on seeds then you might have cooked or drowned them. Some old seeds I had that and I crack a few open to see and they were just mush. I start all my seeds in rockwool or peat plugs now. The move from paper towel can be a bitch if they start to dry out.

I try the paper towel thing just to see if they will pop but it's tricky on heat or too cold.