Good afternoon my name is ***** ***** will assist with your query.
Most likely the door handle may have failed, or the new interlock hasnt been aligned properly.
To get the door open (as a workaround) please follow the video here.
A new latch for the door would be around £20, if you provide me with the part I can direct you to the exact part on espares.
Based on the tone of your comments I will opt out in favour of another engineer who may wish to assist you.