I assume you're talking about Ex. 21.20-21. First of all, you should know that this is case law, not God's command to beat slaves. God never commanded people to beat slaves, or approved of it. Secondly, you'll notice that the rules for slaves were the same as rules for free persons. The OT affirms the full personhood of debt-servants. Thirdly, if it's the Exodus text you're talking about, the situation (case law) is not "nearly beating your slave to death." It's a far lesser injury, as evidence by the fact that he gets up and ready to get back to work in 1-2 days. That's not "nearly beating your slave to death."

To answer your question, an owner who beats his slave to death is to be punished to the full extent of the law, up to and including the possibility of execution (Ex. 21.20).

If the owner beats his slave, (again, not a situation of which God approves), there is no punishment unless he injures him. If he injures him, Ex. 21.26-27 tells us that the owner is to be punished with commensurate punishment, and the slave is to go free, as a reward to the slave, a deprivation for the master, and to ensure that never happens again. God doesn't approve of beatings.

I have a question about your god: What are the biblical punishments for nearly beating your slave to death?