The motor is for sure not running/pushing all the time. This would drain the batteries in no time. Error 42 means motor blocked. i.e. the Smart Lock can not turn the key, because there is too much resistence. Could be that your cylinder is broken.
If - for whatever reason - the Smart Locks clutch does not work anymore you should still be able to unlock with a key from the outside.
Another thing you could try, but is unlikely to have any success, is to reboot the Smart Lock. You can achieve this through a trick by going into Menu > Help > Factory Reset > Smart Lock. In the first step in this flow the App will reboot the Smart Lock and ask you to keep the button on the Smart Lock pressed (which you can’t, therefore no factory reset will happen).