This is a customer-helps-customer forum, so we cannot check anything.
But regardless, don't assume the ride is ended. Call the customer service, or reach out to them via Twitter or Facebook. You can find contact details here: https://www.ns.nl/klantenservice/contact
Worst case scenario is that the bike gets lost and then you'll be charged a couple of hundreds of euros!
To check your ride is properly ended, especially with those electronic locks where you don't physically hand in a key anymore, it's a good idea to enable “OV Fiets ritinformatie” in the NS app.
You'll find that option by going to “Meer” and then “Mijn NS” in the app. There you'll find a button to enable it, which you'll be able to do by entering the number of the bike your using at that moment. Afterwards, it will show immediately after handing in a bike that the ride is properly ended.
The problem sounds familiar by the way, there are multiple topics on this community about the exact same issue. Had problems myself also once and that was a bike being locked for minutes only. That one however unlocked after trying several times.
Welcome to the NS Community!
Contact NS Customer Service (phone preferred +31 30 751 5155 press 5 for English then 1) to explain the situation and have the rental period ended per September 30.
The rental period only ends when a bike is returned to an OV-fiets location (with a €10 surcharge for returning to another location).
With the new electronic locks, it really needs to be ‘seen at home base’ (via Wifi) before the rental period is ended.
Having a bike picked up from anywhere else would cost €50 but if it's (registered as) defective you should not be charged.
