No other tests, but it sounds like new key time, even if they appear to work, if the code is lost it will never synchronise.
The receivers never fail (at least I've never known one to) and they are an universal part, not linked to an individual system.
However, generally "all" Renault roof Aeriel's leak and this water gets onto the contacts of the receiver.
I would suggest removing the aerial and putting some instant gasket under the locating peg and the bolt mount to seal it.
Then give the contacts on the receiver a clean with WD40 or similar.