push open
擺 centers on the action of pushing something open, using physical force to create an opening or spread something apart.
擺 combines 扌 (hand) with 罷, which likely contributes the sound and may relate to spreading or opening. The exact historical development is uncertain.
The hand radical 扌 beside 罷 suggests using your hands to push something open, like spreading curtains or forcing a door apart.
For ハイ, imagine pushing open a heavy door with a loud 'Hi!' as you exert force: Hi -> ハイ, and the door swings open.