Most likely there is a DE Grid with a tear in it, or not seated properly. You'll have to take it apart and inspect each grid. Make sure they're seated properly into the base manifold.

Hey, at least your pump is running...

Step by Step...one item at a time. You'll get it working and you'll have yourself to pat on the back.

I give you credit for perservering. It'll come easier and just think, when you're done, you'll know more than the average pool company.