siemens wireless thermostat

Old Siemens reciever https://i.imgur.com/5nzTFkW.jpg New Hive https://i.imgur.com/lqLys57.jpg I wired this up yesterday but no lights came on at all, checked the wiring and it all looks fine, figured it was a faulty receiver but not sure. One thing I'm thinking is that I know the siemens...

I have a Hive to replace the simple mechanical timer and Siemens wireless thermostat for my Baxi combi boiler (see photos). Before starting I would appreciate advice on the following; - Do I remove the existing timer entirely (it is fitted in the lower boiler case)? - Will the Hive receiver fit...