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Ledger Nano S came out with this new feature (Recovery Check) to test your 24 word password at the end of July 2018, and implemented as an app that can be installed using Ledger Live (see
https://www.ledger.com/pages/ledger-live). I tried it back then and it worked fine. You take a little while to enter the 24 words, but are fortunately spared the burden of fully typing every character of every word on Ledger Nano S (after you “type” a few character for a given word, you can use the device’s up and down buttons to select from a bunch of suggested words that match the prefix you entered, thus saving you the extra character input).
Before the release of the app, you would have needed to reset the device and use the real restore process, so effectively, you could only test the 24 word seed by performing a complete recovery, with all that the process entails…