Diagnosis
Three beeps usually means it doesn't think the lid is closed properly, even if it is. It's a communication failure between the latch and the main control board.
How to Fix It
First, ensure the lid is completely flush. Check for any small items (like a sock) caught in the seal or latch area. Unplug the washer for 5 full minutes. This resets the control board. Plug it back in, close the lid firmly, and try a cycle.
If That Didn't Work
The lid lock switch is likely the issue. The micro-switch inside the latch assembly can fail, sending a bad 'open' signal. The lid lock replacement is the fix.
Heads Up
Don't just keep slamming the lid. If the control board is getting a bad signal, it won't start no matter how hard you close it. The reset is your free first attempt.