Issues with M645 1000s and AE prism finder

I recently bought a M645 1000s with the AE prism finder. Last night I removed the prism finder to clean the focusing screen and now I cannot get the prism to lock back on the body. It feels like it seats on the body but the engaging locks are not locking. The little button to release the finder and won't pop out. I've read the instructions a dozen times to no avail. The prism has both a release button and a button to release the release button.