If you have wired it up as before and you have done the same with the new thermostat it should work, but it's hard to fault find with out doing the basics first......
The resistance of the new element needs checking to make sure that it's within the working parameters .....
First of all you need to check the Ohms on your 230v element as it's 140w a new one should read 230 x 230 / 140 = 377 Ohms or there about's and it should be pulling 0.6 amps (140 / 230 = 0.6)
If the readings are around the range given your element is working so the fault lies elsewhere. If you have a
clamp meter place the clamp round one of the brown wires ( the one from the thermostat to the element ) and when it's switched to AC amps you will be able to see power being supplied to the element by turning the thermostat on and off. If you don't get a reading then check that you have got the wires on the correct connections on the thermostat ( I presume you took photos of how it originally was ? )
Have you checked that there is power getting to the thermostat ..
one of these come's in at times like this