Right
恩 supplies the sound — ēn shifted to èn, only tone differs.
恩 itself stacks
因 (cause) over
心 (heart) for 'cause-of-heart, kindness'; here the meaning doesn't carry. Pure phonetic.
摁 is mostly colloquial and modern, much rarer than its near-synonym
按, but distinguished by being specifically finger-pressing.
摁门铃 'press the doorbell' is the classic example.