First time poster. Here's my problem.

I have an old shower system (different hot and cold water faucets). Today, when I turned on the shower, the HOT water faucet broke off and water started gushing out. I quickly turned off the water supply.

I then replaced the cartridge since all the o-rings and springs drained down when the water gushed. I put everything back together and when I turn on the water supply, the water does not stop coming out from the spout (let me clarify - it is not LEAKING a small amount, but water is coming out like the faucet is on - HOWEVER, the faucet is in the off position. When I take it to on position, the water level increases even more, but in the off position a lot of water is still coming out like the faucet is in the on position).

What is wrong?