How can I open PowerShell via AutoHotkey?

If you are in a 64 bit version of windows, you would need to set the execution policy for both 64 bit powershell and 32 bit.

This means you need to run the same command in both a 32-bit powershell session and 64-bit powershell session. For 32-bit powershell, just search for "Windows Powershell (x86)" in the Start menu.