Sounds like it could be the locking solanoid / actuator isnt kicking in. You will probably need to remove the door card, and have a look at the system, its probably seized so a dose of WD40 or oil should help to release it
NOT WD40!!!!!!!!! Unless you want to be replacing your entire C/L module in six months - it's a penetrant and will destroy soldered joints. You should not use it anywhere near electrical circuits. Ever.
Get some proper electrical contact/switch cleaner.
I tend to refer to all lubes as WD40 - my bad!
oil on mechanical parts and electrical contact cleaner elsewhere as BigD says.